It is all in the name really. They are blue, they are acrylic and they are Square. Definitely Cufflinks as well - quite a large cufflink. The photo shown is a clear blue colour but the stock available has darker patterning on it. Plated cufflink with acrylic insert.

Dimensions (LxWxH): 20mm x 20mm x 6mm (approx.)
Weight per cufflink: approx. 10.59g (heavy)