These sew-ons were made from about the 1920s to the 1960s and were mostly pressed in special molds and then either coated or just using colored glass. They can be used in many ways: make unusual jewelry threading the stones either with yarn, with fine elastic or fine wire. Some dark ones I dyed with Deko-Master floral spray (my favorite, sadly not available in Europe), placing the stones in a box, spraying and shaking. Repeat if needed. The paint dries fast. Leave for at least 24 hrs. by which time the paint should be quite firm and durable. Or decorate the larger ones with decals used in nail art. Make buttons, earrings, make grelots for bonnets and hats - the possibilities are endless.
Muggel (Mu) = Round, smooth sew-ons
Flissel (Fl) = Round facetted sew-ons
Hex = hexagonal shape
Pointed Oval (PO) = As the nbame says: shaped like a boat
Pointed Oval facetted (POf)