Portuguese Gold Coins (Around: Joao V ~ 1720 )

PS: how to determine their gold contents (I believe their are blends?)
How much was the gold content of coins in that time they were made?
Is it 935/1000, or did this vary over the time?

You can take the coins to a jeweler. They will be able to tell you the gold content.

Of course we are always interested to see photos so we can better help.

Sounds like a very exciting find!

OK, I had a look around in the Internet: Portuguese coins from Goa seems to be very rarely sold.
I found some indications of gold contents for most coins from that era at around 90-92%, but one coin seems to have been minted at 80% purity only. I don't know why, or did the author made an error ?

Yes, the quality of minting is not the best, but we recover them on land. Somehow they are the same average quality as some that are sold or at numistasite ( https://en.numista.com)
Some specimen are hardly recognizable though.
Might be a wreck that was washed on shore, and the land advanced.

I'm not sure if the internet informations that I found are trustworthy: I think I should better get some specialized books, or similar.
Some write quite some nonsense, others seem to exibit coins that are much superior in minting to the Goa mint. I wonder if they are faked, or where imported (in Brazil the minting seemed to be far more advanced).

===
The jewellers @tdziemia :
They just have test sets (liquids, you rubble some from the piece and put a liquid over it) for their jewellery: fixed to 925/1000, 750/1000, etc. I don't think they are that exact, I believe they just look at the stamp mark and have it confirmed by these tests. (the coins haven't any)


@Sap (regarding: then going through a European auction house )
Oh, no, in Reunion we already have duty on gold (more than 20% + VAT. And then in France (or Europe) again VAT. They would eat everything.
I think South Africa is free: I'll check it there.
(ps: how do you handle it in Australia ?)

In Madagascar they would even steal everything (I remember there were some searches, a few years ago.... )
Frequently I also find in the news: they chopped somebody with 10 or 20 kg (extracted illegally) at the customs: but for sure: once they find it, it's gone.
Those guys smell it. I think South Africa should be the best, don't want to die having been deposessed. Export tax for gold is already 20% in Madagascar, maybe also VAT applies (another 20%), I understand why everybody tries to take it out without declaratng anything: they are too hungry. Something like 10%, that would be ok.

===
The silver coins do not seem to be worsewhile: with a collectors value of something like 45-60USD, I would have to spent more time in cleaning/restoring them. Thinking about melting them down and sell it locally. I would spent 5 years......
Again, I'll check with some jewellers, maybe they are interested in this. Or they have some specialized cleaning products, for me it's out off question to spend more than an hour in cleaning them.( rather stained and partly sticking to each other)
===
Well, I'll look for some specialized book or paper, and I'll get me some more exact test products (for the purity) first. a more exact balance also (mine just shows 0.5 gr, some kind of household balance)

So, I'm in no hurry.

===
Astonishingly the high rate the Portuguese lost ships:in some years only 20% of their fleet made it back !
More than 250-300 ships they lost over the years. There must be some more wrecks around. I know only of some 4-5 wrecks that had been found. They must have had astronomous profits: Portugal was running out of sailors.

==
This information seems to be the best on the internet:
PORTUGUESE GOLD COINS FROM
GOA (1706 - 1777)
https://oldhistoricity.lbp.world/Ad...icle/178.pdf

I found another pretty good overview of the coins in Goa:
Dinheitro Luso-Indiano, from 1975:
https://archive.org/details/dli.ern.../n1/mode/2up

Unfortunately very poorly illustrated. I can hardly recognize or determine anything about it. The quality is too bad.
I have the impression that these books do not depict all types of coins either. Has the knowledge about this been lost or have the coins been melted down over the centuries? (which would make sense to me, the Indian ones, they really weren't high quality coins).

In any case, I have a few individual coins that are not known at all or are not listed as known from these books.
Are all these books simply a relic from the 1970s, or were there accurate registers from Goa? Or were those books written after the guys who made it to Portugal, and what was not melted down?

I'm still suspicious of the whole thing
@tdziemia: "A larger jeweller will have XRF (x-ray fluorescence)"
Oh no, you don't seem to know Madagascar: there is only one "jeweller" with this word: the remaining are just cabanes & merchants of anything. Mostly some chains, that sell "everydays burgers wedding rings". Yes I believe, there is an XRF searching thing, but only one: in the central bank that robs the other merchants.
I'm pretty sure, nobody has one of this:
https://en.wikipedia.org/wiki/File:...toXRFPic.jpg

PS: I might do another travel to Madagascar during this year, to search for more coins & informations: in museums, and the like are sometimes some on display, but mostly single coins.

Also, I know some guys that collect everything of "ancient" they might have some in their possession.
Example: a hotely that I know, the owner seems to buy everything from ancient forloader guns, to ancient sakay (spears), he might have some more coins in his reserves (or anywhere).

Hate to say it

@tdziemia - thank you very much ! I got inscribed at that side: but still the prices can only be seen by "paying customers": ok, another time, I already have an idea now.

===
I found the books I was looking for !, as pdf:
https://www.numismatique-tours.fr/p...de-portugal/
Descrição geral e histórica das moedas cunhadas em nome dos reis, regentes e governadores de Portugal € 132.00

At least the first volume is available as pdf. (I haven't yet searched for Vol 2 & 3):
https://dn790006.ca.archive.org/0/i...araguoft.pdf
Seems to be a very old language (it's Portuguese)
With excellent drawings of the coins, the author even treats fake coins (yes there were some who brought barrels of copper coins from.... England....
and they are also illustrated: that's already enough for me to start to work with.
I'll be even more happy if I find vol.2 & 3, as the vol. 1 ends shortly before (I thing with King Sebastiao )
Some passages are very difficult to read; for instance the weight, and purity: he discribes them in graos (ancient Portuguese measurement), etc. Luckily they are still used in Brazil
there's even a calculator: graos em gramas: https://www.metric-conversions.org/...m-gramas.htm

Another good German book I have found, editioned by the Deutsche Bundesbank: Neuzeitliche Goldmünzen
https://www.bundesbank.de/resource/...zen-data.pdf
(= Gold coins of modern times, they seem to start at around 15.hundred. No Portuguese Indian coins, but continental Europe & Brazil. They have easier calculation methods for the degree of purity, etc (editioned 1985, and excellent images) : for those that are interested in Gold coins in general, it's certainly a big plus.

====
Some images from the pdf of the portuguese book:




-(the third images show some fakes of portuguese coins)