K9 Optical Crystal
Not glass, not acrylic. K9 optical crystal is cast, annealed for 24 hours and polished on all six faces so it stays clear for decades.
Materials
What the crystal is made of, why it costs what it costs, and how to keep it clear for thirty years.
We use K9 optical crystal — the same family of material used for camera lenses and laser windows. It is harder than window glass, has far fewer inclusions, and crucially it is cast and annealed rather than rolled. Every block spends 24 hours cooling in a controlled kiln so that internal stress cannot build up and crack it months later.
Acrylic is cheaper and will not shatter, but it yellows under UV within a few years and it scratches if you look at it wrongly. We do not use it, and we do not sell it.
Six faces are polished, not just the front. Edges are bevelled by hand on a felt wheel, which is why no two blocks have an identical corner. Every crystal is inspected under a loupe with the engraving lit from below; anything with a visible scratch, a bubble on a face, or an engraving that reads softer than the approved proof is set aside and remade.
The base matters more than people expect, because an engraving is only as visible as the light passing through it. We stock three:
Very little is required, which is the point of buying crystal rather than paper:
Crystal is glass. The engraving will not fade or wear out, but the block can chip or crack if it is dropped or subjected to thermal shock. Keep it out of the dishwasher and away from hard knocks. If it arrives damaged, photograph it and email us — we will make it right.
Not glass, not acrylic. K9 optical crystal is cast, annealed for 24 hours and polished on all six faces so it stays clear for decades.
A focused laser fractures thousands of micro-points inside the block. Nothing is cut into the surface, so nothing can wear off.
Every block is bevelled and hand-polished. Sharp edges are rounded, corners are checked under a loupe before it is packed.
Our LED bases edge-light the crystal so the engraving scatters light and the portrait appears to glow from inside the block.