A rare 17th century gold coin of “unprecedented” quality and valued at more than £160,000 is to go on sale.

The hammered gold Spur Ryal, which dates from 1619-20, during the reign of James I, is said to be “perfectly struck” and thought to be the highest calibre piece of the handful currently in existence, said the Royal Mint.

It is part of a series of centuries-old coins being sold by the 1,100-year-old organisation on Tuesday.

Rebecca Morgan, head of collector services for the Royal Mint, said: “The incredible quality of the Spur Ryal is unprecedented.

“We rarely see a piece as high quality as this, so we were delighted to have sourced the coin and make it available to keen collectors who want to add to their existing collections of historic coins and artefacts.”

The coin derives its name from the sun and rose motif on its reverse, said to resemble the star-shaped revolving disc of a spur, called a rowel.

It was created in “extremely limited numbers” during the reign of James I and just 20 pieces are known to have survived, with this one thought to be the least tarnished, the Royal Mint said.

The coin has been valued at £162,750 and will go on sale at 9am on Tuesday.

Ms Morgan added: “We’re seeing an increasing number of people – not just traditional coin collectors – who are looking to own a unique small piece of history, which acts as both an investment and a keepsake for their collection.

“The Royal Mint’s coin-finding and authentication service draws on original documentation and the latest technology to provide customers with complete confidence that coins are genuine, and help them to create a collection with purpose.”