Britain’s Royal Mint is marking the 350th anniversary of the first striking of the guinea coin with a £2 coin.

Individual precious metal versions are now available, following the release in January of base metal Uncirculated and Proof and silver Proof examples, released as part of the Royal Mint’s annual sets.

Silver Proof, silver Proof piedfort (double-thick) and Proof gold versions of the £2 coin are now offered, with delivery due in July.

The guinea was the principal British gold coin issued from 1663 until 1813. Originally struck as a 20-shilling coin, the guinea’s value in silver fluctuated with the price of gold, reaching some 30 shillings by the reign of William and Mary at the end of the 17th century. In 1717 Master of the Mint Sir Isaac Newton, set the guinea’s worth at 21 shillings — or one pound and one shilling.

The coin’s name comes from the Guinea Coast of Africa, where the royally chartered Africa Company mined some of the metal used to strike the coins.

The 2013 £2 coins’ reverse, designed by Anthony Smith, was inspired by the heraldic shield of the Royal Arms used on the “spade guinea” of George III, issued from 1787 to 1799. The shape of the shield resembles that of a garden spade.

The edge inscription of what is a guinea? ‘Tis a splendid thing, is taken from an 1809 book by Stephen Kemble. The inscription on the reverse of the 2013 coin, anniversary of the golden guinea, refers to the fact that the guinea was always struck in gold. A circle of 150 dots represents the 150 years that the guinea was minted.

The obverse bears the Queen Elizabeth II effigy by Ian Rank-Broadley.

While the circulating £2 coin is ringed-bimetallic, the standard and piedfort Proof .925 fine silver versions have gold-plating meant to replicate the look of the original guinea. The Proof gold coin has an outer ring of .9167 fine red gold surrounding a core of .9167 fine yellow gold.

All the 2013 guinea coins measure 28.4 millimeters in diameter.

The standard silver coin weighs 12 grams, while the piedfort version weighs 24 grams and the gold version weighs 15.97 grams.

Both silver versions have a mintage limit of 4,013 pieces, with 2,000 of each available individually. The standard silver coin is priced at £50 and the piedfort version costs £100.

The gold coin has a mintage limited to 1,110 pieces, with 1,000 of the coins offered individually for £1,000 each.

Telephone the Royal Mint toll free at 866-519-7298 or visit its website, www.royalmint.com.