Diamond is a classic sparkling white shimmer top coat, meant for layering over other polishes. The shimmer particles shine silvery white with a little bit of iridescence, showing traces of pink and aqua among the silvery sparkle. It reminds me of light on fresh-fallen snow - mostly sparkling white but within all the white sparkle there are points of iridescence. 

Rather than offering sets, purchasing three or more bottles of polish from the Gemstone collection in a single order will give a discount of 3.5% on all Gemstone collection polishes in the order, which will be reflected in the cart under the line "Gemstone collection discount."

The last photo shows what Starlight Polish 15mL and 7.5mL bottles look like.