Tiffany & Co. Vintage 18k Yellow Gold Infinity Band Ring Size - 4. This is a authentic vintage band ring from Tiffany & Co. It is crafted from 18k yellow gold with a polished finish and features an infinity design at the front of the band. It has an open design and is signed by the designer with the metal content. Material: 18k yellow gold Hallmark: Tiffany & Co. 750 Measurements: band is: 0.27" wide x 0.10" high Ring Size: 4 Weight: 3.9 grams Stock# 57001