This is a set of tuxedo shirt studs made by Krementz and cufflinks made by Dolan & Bullock. It appears to be a matched set, so perhaps the cufflinks were subcontracted to D&B by Krementz, or someone mixed and matched the set. The set comes in its original Krementz box. Krementz is famous for their plating process and they generally used 14k gold as their coating of choice, although sometimes they used platinum. The centres are mother-of-pearl shell and the side casing on this set is silver toned, so could be white gold plated or silver plated. The back of the cufflinks are stamped “Rolled Plate Back - Correct D&B” - “rolled” gold is a process that deposited more gold on the base metal than electroplating. Dolan & Bullock was founded in 1917 and known for their cufflinks while Krementz was founded in 1866 and made their fortune manufacturing collar buttons, making most of the collar buttons in the world, so the mixed set makes sense. I’m unsure of the exact age of this set, but the box looks to me to be 1920s-1930s period. The set looks to have seen little use.
This is a very attractive set of dress studs and cufflinks, simple and easy to use - nice set!