The black sand is made of volcanic origin from Martinique - Anse Noire.
The white sand comes from the Seychelles - "La digue Island" - Anse Severe. This sand have a lot a red/purple particle, probably small pieces of coral.
The brown sand comes from a dune in the Moroccan desert.
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Lighting is too flat. The way you filled the cup is good, and the patterns in the rim of the glass are also good. The tray of sand underneath, though, detracts from the cup.