A Mistake or Compliance ?

[Joydeep]

Their are three types of British Trade Dollars based on the minting location (i.e. Bombay Mint, Calcutta Mint & London Mint). The coins minted in Bombay-INDIA have the 'B' mint mark at the tip of the middle prong of the Trident held by Britannia, whereas the coins minted in London have no mint marks whatsoever. The following coin has the 'B' mint mark, but is simply designated as the 1930 Trade Dollar on the NGC Slab. Is this by mistake or does NGC simply comply with the Submission Invoice of the sender as far as designation is concerned ?  

[Conder101]

If the B is there (and I'll have to take your word for it, I blew up the image 400% and still couldn't see it) then it is a mechanical error and NGC will fix it for free.  If the submission didn't indicate the mint mark then there is a good chance it wouldn't be listed on the label.  The people entering the form information into the computer, probably try to check for obvious things but probably pretty much follow what is one the forms.  The graders don't enter that information they just grade.  The finalizer should also check to make sure the coin matches the label but some will still get past them.  Especially on a series they might not be real familiar with. (No one knows every series.)

[physics-fan3.14]

I'm not familiar with this series. Where is the B mintmark located? 

[Joydeep]

18 hours ago, physics-fan3.14 said:

I'm not familiar with this series. Where is the B mintmark located? 

I have made a sentence slightly more visible in the first post regarding your query. Besides, I came across this as a listing on eBay. I think it might still be there if you wanted more info on it.

[Star City Homer]

I just flipped through the 1930 NGC trade dollars and it's hard to see, but the B is quite tiny and contained fully within the tip of the third trident prong.  Too pain in the tush to post screen shots, but it does look to be the case.  A mechanical error that NGC will correct.  Is it much of a price difference?

[physics-fan3.14]

I'll take your word for it, and appreciate the clarification. I didn't realize the MM was so tiny. 

If it is there, then yes NGC will correct it. I've got a Moroccan coin with privy marks from Poissy that they've labelled as Paris, and I've seen them correct similar mistakes before. 

[Star City Homer]

I should have written, middle prong and I left out the ones I was checking were the eBay listings.  It's REALLY hard to see.