These are royal blue iridescent venetian tiles. As with most vitreous tiles, there are ridges on one side for better adhesion, while the other side is smooth for a lovely finish. They can can be used whole, or nipped with tile nippers.
100 grams is approximately 33 of these tiles.
They are 3/4" x 3/4" x 1/7" thick. (20mm x 20mm x 3.6mm)
