Super Good Advice: Don't Wipe Autographs

Have you ever had one of those moments when you do something, immediately realize how stupid you are for doing that, and wish you could instantly go back in time just 10 seconds so you didn't do that stupid thing?

That's exactly how I felt when I ruined a perfectly good 2016 Panini National Treasures Jared Goff RPA #/99.  

I've been wanting one of these cards for a while.  I'm a little picky about the autographs because so many of his autographs on these cards are super streaky.  I patiently waited, looking around for the one card I liked which a decent non-streaky autograph.  Finally, I found one.  I bought it.

And upon receiving it, I promptly decided to inspect it before storing it away in my PC.  I did the usual examination.  I checked out its corners, edges, centering... and surface.  To my disgust, there was a fat greasy fingerprint right on the autograph.  I'm not sure if it was there before the card was signed or after, but it was right on the autograph and fairly noticeable under the right light.

Knowing that if this card was submitted to BGS for grading that the finger print would be visible, I decided to try and clean it off.  

I've been in the hobby for how long now?  Oh, about five years.  You'd think I'd know better.  I do.  I did.  But for some reason I decided to just ignore what I knew: don't wipe autographs.

I took a soft microfiber cloth and very gently wiped over the autograph to see if it could take off the greasy fingerprint.  To my pleasant surprise, it did, a little bit.  

The autograph wasn't affected.  

I decided to push my luck.  I gently wiped the card again.  More of the greasy fingerprint was removed, but there was still a big greasy fingerprint streak over the autograph.  

I checked the autograph again.  It was still there, not affected.

And at this point, I think this is where my brain shut off.  I was uncomfortably stooped over next to a desk light so I could see what I was doing, and sort of in a rush to go for a run.  It didn't stop to think, hey, maybe this is far enough.  Maybe if you keep wiping the autograph will come off.  

The National Treasures set features super high gloss cards.  I knew this.  I knew that the sharpie ink sits on the gloss, and does not absorb into the paper which makes it very susceptible to scratching and accidental removal by wiping the card surface with microfiber clothes.  But like I said, my brain sort of turned off for this moment.

I wiped again.  And without thinking, I wiped the card again.  

I checked the autograph, and to my horror, I saw that some of the ink had been wiped away.  It at this moment when I wished I could instantly jump back in time a mere 10 seconds before I made this very stupid decision -- but I couldn't.

I had just ruined a perfectly good autograph.  

What was once a perfect BGS 10 autograph Jared Goff National Treasures RPA, was now a BGS 9 autograph.  Ugh.  

So what have I learned here?  Well, nothing I didn't already know: don't wipe autographs.

You can get away with wiping down autographs on cards with no gloss where the autograph ink gets absorbed into the card stock.  I've done that successfully before.  But as for cards with super high gloss, DO NOT WIPE THE AUTOGRAPHS.  

I feel like a huge idiot for doing this when I know better.  

One other piece of advice I try to follow when I clean cards is TO NOT RUSH.  If you rush, you increase the chances of you dropping the card and dinging a corner or doing something stupid (like wiping the autograph even though you know you shouldn't).  Only clean cards when you're not in a rush.  Sit down.  Put on a bright light so you can see.  Get comfortable.  Take your time.  Move slowly.  Think about what you're doing before you do it, so you can consider whether there is a chance that you'll damage the card.  

Had I not been in a rush, my brain might have not been as distracted and shut off when it should have been telling me DON'T WIPE THE AUTOGRAPH.  

BGS Grading: Centering, Corners, Edges, and Surface

In previous blog posts I've discussed how a card's final Beckett Grading Service grade (BGS grade) can sometimes be more than 0.5 higher than the lowest subgrade.

Remember, the general rule is that a card's final grade can only be 0.5 higher than the lowest subgrade, unless two or more of your subgrades share the lowest subgrade score then your final grade will be equal to that lowest subgrade.  (See this blog post for more information about the general rule.)

But when one subgrade is drastically lower than the rest of the subgrades, the card's final grade can sometimes be 1.0 higher than the lowest subgrade.  However, this exception to the general rule only applies to the edges and surface subgrade.

The Exception to the General Rule

A card's final BGS grade can be 1.0 higher than the lowest subgrade if: (1) the drastically lower subgrade is either the edges or surface; and (2) the aggregate of the other three subgrades compared to the surface subgrade must be greater than 4.

Below are some cards to illustrate these exceptions.

Surface

The general rule is that the card's final grade can only be 0.5 higher than the lowest subgrade; however, in the above Aaron Rodgers card the final grade is 1.0 higher than the surface subgrade.  This is because the lowest subgrade is the card's surface subgrade, and the aggregate difference of the other three subgrades when compared to the surface is 5 (the math is (9-7) + (8-7) + (9-7) = 5), which is greater than 4.

Again, the general rule is that a card's final grade can only be 0.5 higher than the lowest subgrade but in the above Jose Abreu card the card's final grade is 1.0 higher than the lowest subgrade.  That is because the lowest subgrade is surface, and the aggregate difference of the other three subgrades when compared to the surface is 4.5 (the math is (10-8.5) + (10-8.5) + (10-8.5) = 4.5), which is greater than 4.

The general rule is that a card's final grade can only be 0.5 higher than the lowest subgrade.  In the above Cordarelle Patterson card the card's final grade is only 0.5 higher than the lowest subgrade.  This card follows the general rule because although the lowest subgrade is surface, the aggregate difference of the other three subgrades when compared to the surface is 4.0 (the math is (9.5-7.5) + (8.5-7.5) + (8.5-7.5) = 4.0), which is not greater than 4.

The general rule is that a card's final grade can only be 0.5 higher than the lowest subgrade.  In the above Tom Brady card the card's final grade is only 0.5 higher than the lowest subgrade.  This card follows the general rule because although the lowest subgrade is surface, the aggregate difference of the other three subgrades when compared to the surface is 3.5 (the math is (9-8) + (9-8) + (9.5-8) = 3.5), which is not greater than 4.

Edges

A card's final BGS grade can be 1.0 higher than the lowest subgrade if: (1) the drastically lower subgrade is either the edges or surface; and (2) the aggregate of the other three subgrades compared to the surface subgrade must be greater than 4.

The general rule is that the card's final grade can only be 0.5 higher than the lowest subgrade; however, in the above Dan Marino card the final grade is 1.0 higher than the edges subgrade.  This is because the lowest subgrade is the card's edges subgrade, and the aggregate difference of the other three subgrades when compared to the edges is 5.5 (the math is (8.5-6.5) + (8.5-6.5) + (8-6.5) = 5.5), which is greater than 4.

The general rule is that the card's final grade can only be 0.5 higher than the lowest subgrade; however, in the above Matt Barkley card the final grade is 1.0 higher than the edges subgrade.  This is because the lowest subgrade is the card's edges subgrade, and the aggregate difference of the other three subgrades when compared to the edges is 6.5 (the math is (9.5-7) + (9.5-7) + (8.5-7) = 6.5), which is greater than 4.

Centering

The exception that the card's final grade can be 1.0 higher than the lowest subgrade if the lowest subgrade is edges or surface does not also apply if the lowest subgrade is centering.  In other words, even if the centering subgrade is drastically lower than the rest of the card's subgrades, the card's final grade will still be only 0.5 higher than the lowest subgrade.

The general rule is that the card's final grade can only be 0.5 higher than the lowest subgrade.  In the above Reggie Wayne card, the final grade is 0.5 higher than the lowest subgrade.  This is because the lowest subgrade is the card's centering subgrade.  Although the aggregate difference of the other three subgrades when compared to the centering is 5.5 (the math is (9-7.5) + (10-7.5) + (9-7.5) = 5.5) which is greater than 4, that still doesn't matter because the lowest subgrade is centering.

Corners

The exception that the card's final grade can be 1.0 higher than the lowest subgrade if the lowest subgrade is edges or surface does not also apply if the lowest subgrade is corners.  In other words, even if the corners subgrade is drastically lower than the rest of the card's subgrades, the card's final grade will still only be 0.5 higher than the lowest subgrade.

The general rule is that the card's final grade can only be 0.5 higher than the lowest subgrade.  In the above Aaron Rodgers card, the final grade is 0.5 higher than the lowest subgrade.  This is because the lowest subgrade is the card's centering subgrade.  Although the aggregate difference of the other three subgrades when compared to the centering is 10.5 (the math is (9.5-5.5) + (8.5-5.5) + (9-5.5) = 10.5) which is greater than 4, that still doesn't matter because the lowest subgrade is centering.

Centering and Corners are Weighted 

More Heavily than Edges and Surface

What do all the above cards show?  They show that BGS gives more weight to a card's centering and corners subgrades than the edges and surface subgrades.

That might be supported by the fact that BGS lists the centering and corners subgrades first on the card's flip, although perhaps they were just putting the different subgrades in alphabetical order too.

From a collector's point of view, putting more weight on a card's centering and corners condition makes sense.  Those two aspects of the card are usually the most easily discernible to the naked eye, and the most influential aspect of a card's overall eye appeal.

2014 Panini National Treasures and Topps Five Star Football Redemption Shelf Life

In case you haven't noticed, I've been keeping a log of all the redemption expiration dates for football products.  I made that page so people buying older product will know whether the redemptions are expired or not.

One thing I've noticed is that 2014 Panini National Treasures Football has a very short redemption shelf life.  National Treasures went live on April 8, 2015.  The National Treasures redemptions expire on October 08, 2016.

That's a shelf life of only 550 days!

The concern about Panini's redemptions expiring so quickly is moot, however, since Panini will honor expired redemptions.  (Although, at some point in the future they may change their policy.)

Since Topps does not honor expired redemptions there is more concern when buying their products.  2014 Topps Football also went live on April 8, 2015.  The Five Star redemptions expire on February 28, 2018.

That's a shelf life of 1058 days!

Topps gives you almost three years to buy their product without having to worry about hitting a redemption that is expired.  After the redemption expiration date passes, buying a product that is known to have redemptions in it now becomes extremely risky -- especially if the redemptions are of top players.  Wouldn't it be horrible if you hit a redemption of the top QB in the league only to find out the redemption is expired and the card company won't honor it?

Bottom line, when buying older products you should always determine beforehand whether it contains redemptions, and when those redemptions expire!

BGS Surface Subgrade

I found another card which has a final grade more than 0.5 higher than the lowest subgrade.

Remember, the general rule is that your final grade can only be 0.5 higher than your lowest subgrade except when your lowest subgrade is surface.  When your lowest subgrade is surface, and all your other subgrades are significantly higher than the surface subgrade (such as 1.0 or more), then your final grade can be 1.0 higher than the surface subgrade.

In this dual relic card of Aaron Rodgers and Jason Campbell, you can see that the surface subgrade of 7 is the lowest subgrade on the card.  The other subgrades are all significantly higher than the surface subgrade by at least 2.5 points.  This brings the card's final score up from what would normally be a 7.5 to a 8.0.

Be sure to this previous blog post, and this one too, for more information on BGS grading.

Becket Grading Service (BGS) Surface Subgrade

In this previous post I talked about how the final BGS grade is calculated.  As I stated in that post, the general rule is that your final BGS grade can only be 0.5 higher than your lowest subgrade, unless two of your subgrades share the lowest subgrade score in which case your final BGS grade will be the lowest subgrade.

For example, a card with Centering 9.5, Corners 9.5, Edges 9.5, and Surface 9.0 will receive a final grade of 9.5.  A card with Centering 9.5, Corners 9.5, Edges 9.0, and Surface 9.0 will receive a final grade of 9.0.

This rule will work for about 90% of BGS graded cards.  Now, about that other 10%...

Sometimes, when one subgrade is drastically lower than the rest of the subgrades, the final score can be higher than 0.5 more than the lowest subgrade.  This is especially true of the surface subgrade.

The surface subgrade in BGS grading seems to be weighted the least of the four subgrades.

Take a look at the following cards which received a final grade higher than 0.5 more than the lowest subgrade.

Applying the general rule to the Aaron Rodgers card, it should have received a final grade of 7.5 because that is 0.5 higher than the lowest subgrade, but the card received a final grade of 8.0!

Applying the general rule to the Jose Abreu card, it should have received a final grade of 9.0 because that is 0.5 higher than the lowest subgrade, but the card received a final grade of 9.5!

What's going on here?!

The surface subgrade is one of those weird exceptions where if it is drastically lower than the rest of the other subgrades, the final grade can actually be 1.0 higher than the lowest (in this case the surface) subgrade.

But what about the following card?

The surface subgrade on this Tom Brady card is 8.0, and is lower than the other subgrades by 1.0.  Yet this card's final grade is still a 8.5 and not a 9.0.

What's going on here?!

As far as I can tell, there must be some hidden rule coming into play for the Tom Brady card which prevents its final grade from being a 9.0 despite the fact that all the other subgrades are at least 1.0 or higher than the surface subgrade.

My guess is that the aggregate of the difference between all the other subgrades and the surface subgrade is what determines if the final grade can actually be 0.5 higher than the surface subgrade, or get bumped up 1.0 higher than the surface subgrade.

For example, on the Aaron Rodgers card, the aggregate difference between all the other subgrades compared to the surface is:  (9-7) + (8-7) + (9-7) = 5.

On the Jose Abrue card, the aggregate difference between all the other subgrades compared to the surface is: (10-8.5) + (10-8.5) + (10-8.5) = 4.5.

But, on the Tom Brady card, the aggregate difference between all the other subgrades compared to the surface is: (9-8) + (9-8) + (9.5-8) = 3.5.

So, based on these three cards, it appears as if the aggregate difference between all the other subgrades compared to the surface must 4.5 or higher for the card's final grade to get bumped up 1.0 more than the surface subgrade rather than the usual 0.5.

It is possible that the aggregate difference between all the other subgrades compared to the surface must only be 4.0 or higher for the card's final grade to get bumped up 1.0 more than the surface subgrade rather than the usual 0.5, but since we don't have a card with those exact subgrades I cannot confirm that theory.

So, what does this all mean?

I still think the general rule that your final BGS score can only be 0.5 higher than the lowest subgrade is still the easiest way to remember how 90% (or more!) of BGS grades will work; however, I think it's good to know and keep in mind that the surface subgrade is one of those exceptions.  Remember, if the aggregate difference between all the other subgrades compared to the surface is 4.5 or more, then the card's final grade can be 1.0 higher than the surface subgrade.

Beckett Grading Services (BGS) Authentic vs. Altered

While perusing the Blowout Cards forums I saw one interesting post in which somebody asked:

What's the lowest grade you can get on a BGS graded card?

Some people will likely say "authentic," but I believe the best answer is "1". 

First, let's look at Beckett's grading scale which is visible for all to see on their website.  It clearly shows that the lowest score you can get on a graded card is a "1". 

Poor 1

Centering: 100/0 or offcut on front or back. Heavy diamond cutting is allowed. Corners: Heavily rounded or heavily notched with noticeable layering. Edges: Destructive chipping, notching or layering. Surface: Severe print spots. Heavy creases. Severe color or focus imperfections. Heavy border discoloration. Severe stains. No original gloss. Heavy scuffing or a severe tear.

I've never seen a modern card graded that low, but in theory such a score can be obtained. 

So what is an "authentic" grade?  An authentic grade is Beckett's certification that the card contained within the slab is an authentic card made by the manufacturer, and that it's not a fake card or has been altered in any way.

How does a person usually get an authentic grade?  Usually an authentic grade occurs when you send your card to Beckett for BGS grading, and you tell them not to put a grade on the card unless it meets a certain grade of your choice, and if it doesn't then it gets the authentic grade and a blue flip. 

For example, most people will send in cards to Beckett for BGS grading and only ask for a grade if the card grades a 8.5 or higher.  This is because a grade of 8.5 is still considered near-mint, and the slab will receive a silver metallic flip in the slab.  BGS grades of 8.0 or less receive the dreaded white paper flip in the slab.  So because people are afraid to get the dreaded paper flip in the slab -- which doesn't look as good as a silver or gold flip and because the low grade reduces the card's value -- people will choose to just get an authentic grade instead.  This way, when the person sells the card later on, at least it has Beckett's certification that the card is authentic, and the buyer is unaware (unless they examine the card closely within the slab) that the card has some sort of flaws which prevented it from getting a higher grade. 

This is a card with a BGS Authentic grade.

The above picture is an example of a BGS Authentic card.  Note the blue flip, and the words "AUTHENTIC" in the upper right corner.  This card has Beckett's certification that the card is an authentic card made by Panini, from the Epix brand, that the card is not counterfeit*, and the card has not been altered.

(*Side Note: the "authentic" grade only pertains to the card and not to the patch inside the card.  Some people try to increase the value of a card when selling it by taking out bland single colored patches, and putting in fake multi-colored patches.  BGS will still give cards the authentic grade even if the card contains a fake patch.) 

It is important to note that an "authentic" grade is different from an "authentic-altered" grade (sometimes just known as "altered.")  The authentic-altered grade means that the card is authentic, but that it has been altered in some way, usually in an attempt by someone to try and get a higher BGS grade. 

This is a card with a BGS Authentic-Altered grade.

The above card is an example of an authentic-altered grade.  Note that the authentic-altered grade still receives a blue flip, but the flip says "AUTHENTIC ALTERED."  This makes it clear that while the card is an authentic card from Topps, it has been altered in some way. 

In fact, when Beckett Grading Services thinks that the card has been altered in some way, they'll even send you a little note telling you what they think is wrong.

This card received an Authentic-Altered grade because of shaved edges.

This particular Joe Montana card received the authentic-altered grade because the grader believed that the front top, and front left edges were shaved. 

So which grade is lower, an authentic grade, an authentic-altered grade or a BGS 1 grade?

Technically, I believe that the BGS 1 grade is a lower grade.  The authentic and authentic-altered grades are not actually grades per se; they're just statements by BGS that the card is authentic or altered.  A card that receives an authentic grade, could still grade out to be a BGS 6.0 (I'm just picking an arbitrary number) but because the person who submitted the card for grading put a grade minimum of 8.5 or higher, that is why it got the authentic grade.  Similarly, a card which receives an authentic-altered grade could still be in much better shape despite its supposed alterations, than a BGS 1 graded card. 

So if you ask me, I believe that a BGS 1 is the lowest grade you can get when getting a card graded.

A "1 Poor" grade is the lowest you can get from BGS or BVG.

Some people claim that some really beat up vintage cards, which are so beat up that they can't even attain a BVG 1 grade, will get authentic grades.  After perusing eBay for some examples, this claim appears to be true.  The picture below is one example. 

This particular card is in such poor condition it cannot even attain a BVG 1 Poor grade.

So in some cases, yes, an "authentic" grade can be the absolute lowest grade you can get.  But keep in mind that what "authentic" really means is just that the card is legitimate, not counterfeit, and not altered.  Some cards with authentic grades will actually be in much better condition than cards which receive BGS 1 or BVG 1 grades (such as the Brett Favre card, above). 

In conclusion, BGS 1 or BVG 1 is the absolute lowest actual grade you can get when having your card graded by BVG or BGS; however, in some instances, an authentic grade can indicate that the card is in even worse condition than a BGS/BVG 1 although not all the time.  Basically, just use your own judgment and don't automatically presume that a card with an authentic grade is in really bad condition.  It could be in very good condition or better, but it just didn't meet the minimum grade requested by the person who submitted it for grading.

BGS Grading Tip: Ink on Edge Will Result in Low Grade

I was watching a BGS mailday video by UltimateBoxBreaks.com and came across something really interesting. 

One of the cards that was sent in was a Denarius Moore 2011 Panini Prime Signatures 1/1.  Unfortunately, that card came back with a final BGS grade of 5.0!

What in the world caused it to get such a low grade?!   Well, BGS was nice enough to include a note with the card stating why its final grade was so low.  It was because there was ink on one of the edges.

Here's a screen-grab one the ink on the edge.  I've circled it in red.  It's actually a very small ink mark.  It looks like the player (or maybe the owner of the card) accidentally nicked one of the edges of the card with either a sharpie or a ball point pen.  Either way, the results is a really really, and I mean really, bad edges subgrade.

I even looked up the BGS grade online.  Here it is.

The edges got a 4!  This just goes to show how careful you have to be handling your cards, and inspecting them for flaws before you send them in.

(And as a side note, it is worth noting that the card's final grade was a whole 1.0 higher than its lowest subgrade, which is a rare exception to the general rule that you can only get 0.5 higher than your lowest subgrade.  Check out this Beckett BGS Grading blog post for more information on that.)

Now, I've already blogged about the ink stain problems on 2013 Topps Five Star Football cards.  Imagine if you sent one of those cards in for BGS grading.  You'd probably get just as low of a grade, or perhaps even a lower grade.  I've seen some 2013 Topps Five Star Football cards with big time ink stains on the corner edges -- much bigger than that little ink mark on this Denarius Moore card.  It would be such a shame if you hit a really nice card in your box of 2013 Topps Five Star Football only to find out that it had ink stains on one of the corners.  Since you would only expect that card to get a final BGS grad of about 5.0, then its value would be incredibly diminished.

UPDATE:  Since I wrote this blog post, UltimateBoxBreaks.com did another Beckett BGS Grading mailday video, and two 2013 Topps Five Star Football cards came back upgraded because of ink stained corners.   Apparently the ink stained corners were so bad that BGS didn't want to grade them.  I'm assuming that the grades the cards would have received would be even less than a 4.0. 

Sports Card Thickness

If you haven't checked out BCW's blog, you should.  They have some great tips on their blog and plenty of information about their products.  One great blog post is the one on card thickness.  If you can always remember the below tips, you'll never have a problem with knowing what thickness magnetic or toploader that you need for your cards!

• A regular sports card is about 20 points thick.
• A regular Topps base card is about 18 points thick.
• A card sleeve is about 4 points thick.

Basically, all you need to remember is that your typical sports card is 18 to 20 points thick!  If you can remember that, and you have some extra base cards lying around, you can always figure out the exact thickness of a card by stacking those base cards next to it.  This is a great way to figure out what size and thickness magnetics and toploaders you need. 

eBay Best Practices: Communicate with the Seller Regarding Any Problems

You've just received an item in the mail from a seller on eBay.  You open up the package only to discover that something is wrong with the item.  Perhaps it was not as described or it was partially damaged in transit due to poor packing protection.  What do you do?

It's always a good idea to politely contact the seller and notify them of the problem.  Most sells will respond and offer you the ability to return the item for a refund.  Sometimes if they're feeling super generous they may refund you part of the sale price or let you keep the item.  Other times, they may even reimburse you for return shipping costs although those are normally borne by the buyer.

In any event, politely communicating with the seller is never a bad idea.  If they don't respond to messages to help resolve your problem then you should feel no remorse for leaving them neutral or negative feedback.  (As of the date of this blog post, eBay sellers can only leave buyers positive feedback so you should have no fear of receiving a retaliatory negative feedback.)  Your last resort to an unresponsive or uncooperative seller is to open up an eBay claim.  As long as you have messages and pictures to prove your story, you should be able to convince eBay to rule any disputes in your favor so you can get a refund. 

Beckett Grading Service (BGS) is NOT an Average

One misconception a lot of people have with Beckett Grading Services (BGS Grading) is that the "formula" is an average.

Here's a tip:  BGS does not use an average. 

I've covered the basics of the BGS forumla in this previous blog post. 

BGS gives more weight to your lowest sub-grade(s) than your higher sub-grades.  For example, if a card has sub-grades of Centering 9.5, Corners 8.5, Edges 8.5, and Surface 9.5, the final grade will be NM/Mint+ 8.5 and not a final grade of 9.0 which is the average.

Centering 9.5
Corners 8.5
Edges 8.5
Surface 9.5

Average = 9.0
BGS Final Grade: 8.5

Remember, if two of your subgrades share the lowest subgrade score, then your final grade will be equal to that lowest subgrade.  

How to Verify the Authenticity of PSA Graded Cards and Flips

One great way to determine if a PSA graded card is authentic and not counterfeit or fake is to use the app "RedLaser."

The app is free, and is available for the iPhone.  Use it to scan the PSA barcode on the "flip" (the paper tab at the top of the slab which has all of the card's information printed on it).

RedLaser will read the barcode, and show a number.  That number should match the serial number shown on the flip.  If it doesn't, that means it's a fake!

Keep in mind that even if the barcode matches the serial number, it could still mean the card is fake or the slab has been tampered with in some way.  But this is one great and easy way to determine if a slabbed card is counterfeit or not.

Try it yourself!  Below is a PSA 10 Michael Jordan rookie card.

If you use RedLaser to scan the barcode, it should read the barcode as "90576975" instead of "90168589" which is printed on the flip.

Clearly, this flip is fake and the card inside the PSA slab is likely counterfeit too.

Beckett Grading Service Formula

I've been trying to figure out the Beckett Grading Service (BGS) "formula" in my spare time.  I've been looking at BGS graded cards on eBay and COMC.com to help narrow down the exact "formula" that BGS uses.

For the most part, it's fairly simple.  It goes like this:

• Generally, your final grade can only be 0.5 higher than your lowest subgrade. 
• Exception: If two or more of your subgrades share the lowest subgrade score, then your final grade will be equal to that lowest subgrade.

An example of the general rule would be a card with Centering 9.5, Corners 9.5, Edges 9.5, and Surface 9.0.  The final grade is 9.5.

Another example of the general rule would be a card with Centering 9.0, Corners 8.5, Edges 8.0, and Surface 9.5.  The final grade is 8.5.

An example of the exception to this general rule would be a card with Centering 9.5, Corners 8.5, Edges 8.5, and Surface 9.5.  The final grade is 8.5. 

This general rule and its single exception will probably work for about 99% of BGS graded cards.

Things get a little more complicated, however, when one subgrade is drastically lower than the rest of the subgrades (i.e. a card with Centering 9.5, Corners 9.5, Edges 9.5, and Surface 7).  In such circumstances, the final grade can sometimes be more than 0.5 higher than your lowest subgrade.  For more information about these cards, see this blog post. 

Finally, the subgrade requirement to get a BGS Pristine 10 is very stringent:

• To get a "BGS Pristine 10" final grade, you must have at least three 10 subgrades and any subgrade which isn't a 10 must be a 9.5.  (In other words, you cannot have any subgrades be a 9.0 or lower.)

For example, a card with subgrades of Centering 10, Corners 10, Edges 9.5, and Surface 10, would have a final grade of Pristine 10.

For example, a card with subgrades of Centering 9, Corners 10, Edges 10 and Surface 10, would have a final grade of Gem Mint 9.5.

Just keeping in mind the above general rule and its exception (which will work for what I estimate to be over 99% of BGS graded cards), you will be able to calculate what a card's final BGS grade should be depending on its subgrades.  This knowledge is especially useful if you are thinking about submitting your own cards to Beckett for grading.  By honestly estimating what subgrades your card will receive, you can calculate what your final grade will be based on those subgrades.