What are Shellac and Gelish what are the differences? Shellac as well as Gelish are brands of semi-permanent varnishes. CND and Nail Harmony are the first companies to bring the liquid gel polish to the market. CND named it Shellac and Nail Harmony named it Gelish In the process, the competition copied the product, gave it the name Gel Polish and in Greece it became known as semi-permanent varnish.