Estate Tiffany & Co. Atlas 18K White Gold Diamond Ring is for sale! The Atlas design was inspired by the Atlas clock on the facade of Tiffany's famous Fifth Avenue flagship store. The mounting measures 5.3mm in width, with a thickness of 1.9mm (3.5mm in width where 3 Round Brilliant Diamonds are set). The prong set Round Brilliant Diamonds are F/G in Color with a Clarity of VS2. Size 8. SKU 415-21.