Help with authenticity of a Spanish cob

[ValiantKnight]

So I had recently fallen into a bit of a rabbit hole reading and learning about the Golden Age of Piracy and wanted to acquire a coin that could have circulated in the Caribbean at that time. I conducted some brief internet research in how to identify fakes and also looking up authentic examples for comparison. It still feels kind of impulsive but I ended up buying this 1710 2 reales cob from Lima.
 

It weighs 5.58 grams, around a gram under full-weight examples, but I attribute this to its corroded state which indicates it could have been sea salvage. It looks like it might have some small spots of horn silver as well (can silver coins develop horn silver underwater?). And the strike looks uneven (more noticeable underneath the pillars on the reverse). The shape resembles a few authentic examples I saw and the legends match up so I’m fairly certain it is authentic, but given my very limited knowledge some doubt remains. Thanks for any help with this.
 

(Seller’s photos, will update with my own when it arrives)

 

Edited February 26 by ValiantKnight

[John Conduitt]

I don't know if it's a salvage coin. That's not to say it isn't real, but it doesn't seem to be corroded in the same way. Although that might be down to composition.

Here's my only shipwreck cob.

Charles II of Spain Eight Reales, 1676

Potosí, Bolivia. Silver, 40mm, 17.93g. Pillars; mintmark P / 8 / assayer E (Antonio de Ergueta); PLV·SVL·TRA; POTOSI ANO, date, EL PERV (Potosí, Peru). Quarterly of lions and castles; P / 8 / E / date; CAROLUS·II·D·G·HISPAN· (S-P37b). Recovered from Consolación, sunk after striking a reef in 1681 off Santa Clara Island, Ecuador. A delay in receiving coins from the Potosi mint (which travelled by llama and mule) prevented her from sailing with the rest of the armada. When the lone ship, with a cargo of perhaps 100,000 Spanish dollars, heard pirates under the command of notorious buccaneer Bartholomew Sharp were in the area, the captain decided to ground on Santa Clara Island (‘Island of the Dead’), but struck a reef. The vessel was evacuated and intentionally set on fire to prevent it being plundered. From Daniel Sedwick.

[robinjojo]

3 hours ago, ValiantKnight said:

So I had recently fallen into a bit of a rabbit hole reading and learning about the Golden Age of Piracy and wanted to acquire a coin that could have circulated in the Caribbean at that time. I conducted some brief internet research in how to identify fakes and also looking up authentic examples for comparison. It still feels kind of impulsive but I ended up buying this 1710 2 reales cob from Lima.
 

It weighs 5.58 grams, around a gram under full-weight examples, but I attribute this to its corroded state which indicates it could have been sea salvage. It looks like it might have some small spots of horn silver as well (can silver coins develop horn silver underwater?). And the strike looks uneven (more noticeable underneath the pillars on the reverse). The shape resembles a few authentic examples I saw and the legends match up so I’m fairly certain it is authentic, but given my very limited knowledge some doubt remains. Thanks for any help with this.
 

(Seller’s photos, will update with my own when it arrives)

 

Nice coin!  You're correct about the attribution to Lima, with a blurry by mostly legible "L" in the lower right corner of the "tic tac toe" layout.  The assayer is "H" for Francisco Hurtado.  As for the date, there is a clear "7" and 1", followed by an incomplete number which is likely a "0".  Sedwick, in his cob reference, has two date ranges for this assayer: 1701-05 and 1710, so 1710 for your coin it is.

Your coin has been salvaged, but the corrosion is minimal making this a very desirable coin.  Congrats!

I don't have a 1710 dated cob for this mint.  Here's an 8 reales of 1704, assayer H, purchased from Freeman Craig back in the mid 1980s.

Lima, 8 reales, 1704 H.

KM 34

26.9 grams

Edited February 27 by robinjojo

[ValiantKnight]

19 hours ago, robinjojo said:

Nice coin!  You're correct about the attribution to Lima, with a blurry by mostly legible "L" in the lower right corner of the "tic tac toe" layout.  The assayer is "H" for Francisco Hurtado.  As for the date, there is a clear "7" and 1", followed by an incomplete number which is likely a "0".  Sedwick, in his cob reference, has two date ranges for this assayer: 1701-05 and 1710, so 1710 for your coin it is.

Your coin has been salvaged, but the corrosion is minimal making this a very desirable coin.  Congrats!

I don't have a 1710 dated cob for this mint.  Here's an 8 reales of 1704, assayer H, purchased from Freeman Craig back in the mid 1980s.

Lima, 8 reales, 1704 H.

KM 34

26.9 grams

Thanks so much for the information and help! And that’s a very nice 8 reales. Definitely a collecting goal of mine to get one of my own. 

[robinjojo]

1 hour ago, ValiantKnight said:

Thanks so much for the information and help! And that’s a very nice 8 reales. Definitely a collecting goal of mine to get one of my own. 

You're welcome.  The KM # for your coin is 32.

[ValiantKnight]

So it arrived today. Seems real in hand but I thought it was odd that it had a few minor patches of what looked to be bronze disease. I’ve since removed them. Did Spanish cobs have any copper in them?

@robinjojo

 

Edited March 2 by ValiantKnight

[ValiantKnight]

These two exposed spots look like pure silver (no BD was there)

 

This area was covered with light BD. Silver underneath but the edges around it have a bit of pink/orange (copper?). 

This spot of metal is pink/orange, but it did not have BD.

 

I’m thinking that perhaps the dark patina itself has traces of copper that’s attracted BD (assuming it was BD), or maybe the coin was buried/stored with copper coins, and due to environmental conditions those coins leeched some of their copper onto my coin, or possibly these cobs were minted with some copper in them (what’s the usual silver purity of these?). 

Edited March 2 by ValiantKnight

[robinjojo]

4 hours ago, ValiantKnight said:

These two exposed spots look like pure silver (no BD was there)

 

This area was covered with light BD. Silver underneath but the edges around it have a bit of pink/orange (copper?). 

This spot of metal is pink/orange, but it did not have BD.

 

I’m thinking that perhaps the dark patina itself has traces of copper that’s attracted BD (assuming it was BD), or maybe the coin was buried/stored with copper coins, and due to environmental conditions those coins leeched some of their copper onto my coin, or possibly these cobs were minted with some copper in them (what’s the usual silver purity of these?). 

Silver content can range, based on the period between 93.1 % and 91.7% silver, so you don't need to worry about bronze disease with this Spanish cobs or milled coins.  If you see any green or black deposits, they're usually quite superficial, unless the coin is heavily encrusted, as is often the case of coins salvaged from wrecks.

Nice coin, and a scarcer mint (Lima)!

[ValiantKnight]

14 hours ago, robinjojo said:

Silver content can range, based on the period between 93.1 % and 91.7% silver, so you don't need to worry about bronze disease with this Spanish cobs or milled coins.  If you see any green or black deposits, they're usually quite superficial, unless the coin is heavily encrusted, as is often the case of coins salvaged from wrecks.

Nice coin, and a scarcer mint (Lima)!

Good to know, thanks again! What are the usual mints for cobs? Potosi? Mexico City?

Edited March 2 by ValiantKnight

[robinjojo]

7 hours ago, ValiantKnight said:

Good to know, thanks again! What are the usual mints for cobs? Potosi? Mexico City?

Yes, the largest new world mints for Spain were Mexico City and Potosi, Bolivia (Alta Peru).  The smaller mints were Santiago, Chile, Bogota and Cartagena, Colombia and Lima, Peru (probably the third largest in volume), 

Later in the 1730's the mint in Guatemala began operating.  Guatemala 8 reales are unusual and distinctive in style when compared to the other mints.

Here's an 8 reales cob, flip struck error, with the characteristic hold, from 1740.  The indigenous people created holes in order to put the coins on a string or rope, since their clothing generally lacked pockets.

22.88 grams

 

And here's a milled coin of 1770, virtually mint state:

26.93 grams