18ct Solid Gold: 75% Solid Gold & 25% Alloys (sterling silver for strength). Made for longevity. Where as 18ct Gold Vermeil has 92.5% Sterling Silver base metal and is dipped in 2.5 microns = 0.000025% gold coating. Which will wear off over time. Do not mistake 18ct Solid Gold jewellery for jewellery that is branded as 18ct Gold (vermeil).