Rings › Style #531 Image 1 of 1 Style #531 $0.00 18k gold ring with 7x5mm octagonal cut center stone and 5mm trillion cut side stones. Show in Tanzanite and Pink Tourmaline. Add To Cart Added! 18k gold ring with 7x5mm octagonal cut center stone and 5mm trillion cut side stones. Show in Tanzanite and Pink Tourmaline.