Or, being expensive was the Oxblood mixed, layered, applied, to the base glass in such a way that a minimum ammount was needed for maximum exposure. This is easier for me to imagine than the glass floating to the surface of a marble. The glass came in a stream and I picture the Oxblood glass layered on top of the base in the pot. Sort of (but differently)how the glass is layered to make horizontals. Just my way of thinking. Peace,Galen