Shipwreck Coin! Real?

A lady i buy coins has sent me this coin, the coins ive been buying and are all real, can anyone tell me more about this one? Value, authenthicity?

Please could you send more photos of the coin and its weight and dimensions, thank you :) 

Doesn't look like it spent 220 years in sea water.

A real one:

rsirian1 is right to point it out, I was trying to break it to you lightly, but yes, as he has said, just from that photo alone, we can see there is barely any damage to it. There's a chance it is a genuine 1742, but from what we see, it does not look like it was ever underwater. Hope that helps :)

I have a few shipwreck coins and they can take on different appearances depending on their situations.   
 

I have a similar Mexico 8R from the 1761 “Auguste” shipwreck, recovered in the late 1900s, more than 200 years later.  It is pedigreed and graded, and has the same orange-brown appearance as yours.

I don’t know if your is genuine, but maybe you could ask the seller if he has any more information/ pedigree.

As additional information, this is the listing from Numismatic Finds:

A 107.  

Off  Mauritius  Island,  diving  expeditions in  the 1950s. 

Type  of  find:  Shipwreck. 

Ship:  French  East  India  Company  slave ship Saint  Geran,  which  departed  Lorient  March 24,  1744,  and  loaded  up  with  slaves  at  Goree Senegal. 

Sank;  August  18,  1744. 

Contents:  2+  BI,  2+  AR. 

Description: France,  2 sol,  1743A  (2) Spanish  colonies,  8 reales,  Mexico,  1741  (2) 

Divers  are  also  reported  to  have  brought  up coins  dated  1742. 

Bibliography:  Arroyo  1972;  Bowers  and  Merena 1983,  lots  101-2;  Breen  1988,  51  (Breen  396); Sebring  1986,  120.