How do they make those 3D laser-etched paperweights?

Factual Questions
1

Like this one

If you haven’t seen them, these are intricate, full 3D figures that appear to float inside a block of crystal. When lit from below, they appear almost holographic.

I know lasers are used, but I can’t grasp how 3D figure is created inside a solid block of glass. How can a laser be focussed to create a point of opacity? Wouldn’t the beam pass through all parts of the glass equally?

Anybody know more about how this is done?

2

It’s done using a conical beam. The glass only gets hot enough to fracture at the “point” of the cone.

http://www.bathsheba.com/crystal/process/