In the recent Sincona auction 25, ended on October 14, 2015 this coin was available for bidding (Lot 2048).

Coin weight is 13.41 gm, means about 3.8 times the weight of a single ducat. In the auction catalog it is called a “4 ducats” piece, however when it comes to the Amsterdam piedfort ducats, all their denominations (e.g. 3 ducats, 3.5 ducats, 4 ducats) are antirely artificial.

Amsterdam 1673 quadruple piedfort ducat
(source: www.sincona.com)

The coin is sold for 15,340 CHF = $16,016 = 14,048 EUR (incl. Buyer’s Premium). Estimated price was 13,000 CHF.

The Amsterdam mint minted single gold ducats between February and June 1673. There is no reports about minting piedfort ducats or even about test strikes of these coins minted in the official mint. These coins were minted outside the mint by Christoffel Adolphi – unlike the single ducats – by using the screw press. Amsterdam mint archives do not mention a screw press being installed in the mint, but the appearance of piedfort ducats leaves no doubt they were struck with this method. Coins minted by Adolphi have a lettered edge, all of them are struck with dies of great uniformity and only a small number of dies variants are known (1 for obverse and 2 for reverse). A very extensive research on the Amsterdam gold ducats and piedfort ducats is going to be published in the second volume of this book.

You may see this coin here.