Like many other mints, the Royal Mint issues bullion coins in precious metals, having much higher intrinsic value than their face value. The five ounce (5 oz) silver coins are denominated as ten pounds (£10).
The coins are legal tender but are not intended for circulation. They are targeted at bullion investors or collectors who appreciate the special editions as pieces of art. The coins are typically "one-year" types usually issued in parallel with smaller denominations with the same reverse designs.
This commemorative coin celebrates the Sapphire Jubilee (65th anniversary) of accession to the throne of Queen Elizabeth II.
The Royal Mint says:
"In 1977 millions of people crowded the streets as Her Majesty The Queen made her way to St Paul’s Cathedral to begin her Silver Jubilee celebrations. Many millions more watched on television all across the Commonwealth, little knowing that we would go on to enjoy a Golden and later Diamond Jubilee. In 2017 The Queen will reach an unprecedented milestone of 65 years as Britain’s monarch - becoming the first and only British king or queen to celebrate a Sapphire Jubilee."
The reverse was designed by Gregory Kenneth Cameron, the Anglican bishop of the Diocese of St Asaph in Wales, who also designed The Last Round Pound. | 
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