What do all the different sized marbles do in a slurper set?

They all just move around and make for more cleaning.

The little ball, or pearl do the same thing, they move the oils up and down, while holding extra heat.  The small marble on top is there to just have fun in our point.  It causes more turbulence moving the oils around more.  We guess that is the purpose of all of them, to move the oils around to get a bigger hit.

The last large one allows the top to seal, allowing the air to flow properly.

how is colored quartz made

Much like the same as boro.  But because quartz melts at such a much higher temperature there are not a lot of minerals that work in quartz to make it colors.  Some will fume the quartz

why do opals crack so often?

Opals are not a perfect 33 COE.  Therefor sometimes they can crack in glass, even years later.  This is why Elev8 Premier rarely uses them, and if they do, it goes on a piece that can come off, if it were to crack.

But they are always used because we love the sparkle!

Does Dicro burn?

Dicro can be burned out.  When this happens it looks more white like snow rather than that super shiny metal flake.  It takes skill to get the glass hot, but not too hot.