A synthetic colour-changing sapphire dress ring, comprising a large oval-cut synthetic colour-changing sapphire of 21.7 x 15.5 x 7.8 mm, collet-set to a corrugated surround, in a gallery pierced with foliate patterns, flat shank in yellow metal marked 'K18', ring head 2.8 x 2.3 cm, size T, 13.1 grams.