I create my murrini from a variety of COE 104 glass. The core of this beautiful murrini is a core of deep rich sapphire with a striped exterior of sone colors. Like a mined sapphire, a surprise in every chip. Sizes 3mm-7mm with average of 5-6mm. This murrini comes in packages of 20+ (I always throw in a couple extra). It has a smooth melt, will not scorch and melts evenly on enamels.