Counterfeit French Ecu 1643 A

Very interesting.

Nice find and story with a decent SG test.
This is the kind of coin I like to collect because I think fakes are more interesting.
I sold off nearly all my world coins & all my USA coins because they became too pricey & boring.
Discovering what's right & wrong about counterfeits, with photos & documentation keeps me interested.
I look for coins like this on ebay, but it seems the sellers either think they are legit or they are trying to scam.
Even when contacted, it's rare I ever get a reply to buy a counterfeit at a fair price instead of what they are trying to get.

You've done some very solid detective work here. Let's break down the evidence step by step:
1. Weight and Density
- A genuine 1643A ecu à la mèche courte (Louis XIV, Paris mint) should weigh about 27.5 g with a density close to 10.4 g/cm³, consistent with high grade silver.
- Your specimen at 25.5 g and ~8.5 g/cm³ is far too light and low in density, which immediately rules out solid silver.
2. Composition
- Dealer's test showing 62% copper, 36% zinc is essentially a brass alloy. That's a classic signature of counterfeit coinage, since brass was cheap, easy to cast, and could be silver-washed to mimic the look of silver.
- The missing 2% could be lead, tin, or nickel — all common in brass mixes.
3. Fabrication Clues
- The "hammered/scraped" edges you noticed are very telling. Contemporary counterfeiters often filed or tooled the edges to disguise casting seams.
- If it were a modern reproduction, you'd expect cleaner machine made edges or even a seam from a two-piece mold, but the rough tooling is more consistent with 17th-18th century workshop practices.
4. Historical Context
- Contemporary brass counterfeits of Louis XIV ecus are known. Collectors have documented underweight brass or copper-alloy host coins, sometimes silvered, that circulated alongside genuine silver issues.
- One example: a 1643 counterfeit ecu weighing only 21 g, made of copper alloy, likely silvered originally, and attributed to the mid-17th century.
- By contrast, modern tourist fakes or replicas tend to be pewter, pot metal, or plated base alloys, often with incorrect weights and sharper casting flaws.
5. Likely Attribution
- Based on your data: brass alloy, underweight, density mismatch, and tooled edges this strongly suggests a contemporary counterfeit, not a modern reproduction.
- The fact that it mimics a first-year Louis XIV ecu (1643A) makes it even more interesting, since that was a prime target for counterfeiters at the time.

Bottom line: Your coin is almost certainly a contemporary counterfeit brass ecu, probably silvered originally, and circulated in the 17th century. That makes it historically significant in its own right — not disappointing at all, but a collectible in the CCC tradition!

Contemporary fakes are very interesting for their history.

I think colonialjohn makes persuasive arguments for yours being contemporary. I found the wear strange. But the edge does not look modern at all, it is a good point. And it looks circulated.
You should search and compare to other known contemporary fakes of this issue of similar.

This topic prompts me to dig out & review my ECU's.
I have two: 1726 A & 1782 Q.
I do that sometimes because I have better measuring & photo equipment now so some pages get updated compared to how they look when they were first made.