Blue Topaz Gemstone and Diamond Engagement Ring In the sky with Diamonds - Blue Topaz and diamond cluster, classic style engagement ring. £875.00 £875.00 1 in stock. Blue topaz gemstone, the colour of a dazzling summer sky is surrounded by round brilliant cut diamonds and set in 18ct white gold. Blue Topaz 3.44ct Diamonds 0.13ct Ring Size - M 1/2 A beautiful engagement ring or cocktail ring. We also Offer a Bespoke Jewellery Service if your looking for a unique piece of jewellery, simply contact us.