Watch Glasses are generally used for drying crstals and samples.
They provide a see through, clean concave base, for liquids to gravitate towards the centre, whilst crystallising.
THey have lots of other uses, pefhapds,burning ants, but scientifically speaking, are pretty much the standard in crystal forming.
Watch Glass 75mm
Watch Glass 125mm
Watch Glass 75mm x 10 KIT
Watch Glass 125mm x 5 KIT