18ct Rose Gold Blue John Queen\'s Jubilee Hallmark Medium Rhombus Ring. R607_JFH. As anyone with a love of fine jewellery and its craftmanship will know, the UK hallmark provides a unique and identifying feature to any design. Dating back to the 15th century, UK hallmarking has provided customers with a sign of excellence, origin and approval on all jewellery passed through their Assay Offices for inspection. In a very special year for hallmarking, with the British Hallmarking Council sanctioning a commemorative component mark to celebrate Her Majesty the Queen’s Platinum Jubilee, C W Sellors celebrate these special marks in their new ‘Hallmark Collection’. Across a range of collectable rings, bracelets, pendants, and a newly commissioned ingot design, the hallmarks are brought to the fore to wonderfully showcase the quality of the piece chosen worn. Providing a unique and collectable addition to any jewellery collection, each piece carries the official assay marks of the year it was manufactured - 2022 (X), the makers/sponsors mark – C W Sellors (CWS), the metal standard – 9ct Gold (375) or Sterling Silver (925 & Lion), the Assay Office – Birmingham (Anchor) and the new Platinum Jubilee Mark (Orb). This item will arrive lovingly and securely dispatched in our elegant jewellery packaging.Dimensions: Blue John: 21mm x 21mm.