These machine-cut round Chessboard sew-on crystal stones from Czech brand Preciosa Crystal have a full faceted top with two holes and a silver foiled reflective back. They are made with Preciosa's premium lead-free MAXIMA crystal. Thanks to Preciosa's advanced manufacturing technology, MAXIMA quality stones contain less than 90ppm of lead and barium. Preciosa stones also boast precise sizing and shape, along with highly durable coatings and foiling. MAXIMA crystal stones are compliant with the following world standards: ASTM F2923-11, ASTM F963-11, CPSC 16 CFR 1303, CPSIA, Directive 209/48EU, OEKO-TEX Standard 100 and more.