Cufflinks by Josef Koppmann The cufflinks are made using stering silver and the sapphire is set onto solid 24 carat gold. Designed and handmade by Josef Koppmann. Features Primary Material : 24ct gold and silver Other Materials : sapphires Fitting Type : hinged bar Dimensions (mm) : 30 x 10 x 10 One of a Kind : No Metal : 24ct gold and silver Gems : sapphires Hallmarked : Yes Cleaning InstructionsThe cufflinks are best kept clean by rubbing and brushing them gently under water with bicarbonate of soda. Do not submerge in water for long periods and do not clean the cufflinks in ultrasonic cleaning systems.