George III Gold Proof "Spade" Guinea Coin

A 1787 George III Gold Proof “Spade” Guinea is highly valuable, with average proof examples estimated around $13,000 USD, while standard circulation strikes sell for roughly £550–£1,100+
. Proof versions feature superior strike quality, often achieving high prices at specialised auctions, with rare, top-condition examples reaching even higher premiums.

Proof Value: PROOF examples of the 1787 Spade Guinea are valued around $13,000 USD, according to Coinstrail.
Standard 1787 Guinea Value: Mid-grade “Spade” guineas usually trade around £575–£1,150, says Coin Hunter.
Sold Prices: Auction results (e.g., London Coins) show prices ranging from £550 to over £1,100 in recent years for standard examples.
Record Sale: A notable 1787 Guinea sale reached CHF 36,000 in 2021, according to Coinstrail.