All our memorial keepsakes are hand blown and sculpted in the U.S. by glass artists. Molten glass is at temperatures over 2000 degrees which is a higher temperature then most cremation. When the glass is molten the cremains carefully incorporated into the glass, just like would be done with glass color. Since glass is at a higher temperature then the cremains, the carbon is burned off and the cremains turn a brilliant white color in the glass.