How Do You Get a Galaxy Inside Solid Glass? (Spoiler: Millions of Tiny Cracks)

The first question everyone asks about our 3D crystal gifts is “how did you get it inside?” The answer starts with a surprising fact: glass is transparent, so a laser beam passes through it without doing much at all.

The beam is focused to a tiny point deep inside the block, and only at that exact spot is the energy concentrated enough to cause a microscopic fracture. Everywhere else along the beam’s path, the glass stays untouched. That’s why the surface of a 3D crystal stays perfectly smooth.

The picture itself is made of points. The software turns a photo or 3D model into a “point cloud”, and the laser then fires short pulses, one for each point, while the focus moves through the block in three dimensions. Each tiny fracture is a speck that scatters light. Thousands of specks together make a face, a pet or a galaxy that seems to float. This is also why a crystal looks magical on an LED base: the specks catch the light, and the clear glass around them stays dark and transparent.

There are a few clever challenges. The glass has to be very clear and clean, because impurities scatter the beam before it reaches its target. And if the glass is a ball rather than a block, it acts like a lens and bends the beam, so the focus lands in the wrong place and the picture distorts. Our xTool F2 Ultra UV has an internal engraving area of about 70 x 70 mm, so every design has to fit that space.

 I love that something so magical comes down to careful focus and a LOT of dots. See what we make in our personalised collection.