‎

Know Your Cube

Dichroic cube vs CMY Cube: what's the difference?

They can look similar in a photo. In your hands, they're entirely different objects, doing entirely different things to light. Here's the science, so you know exactly what you're buying.

The dichroic cube

Splits light apart.

  • Made of glass with a thin mirror-like coating that reflects some wavelengths and lets others pass.
  • The rainbow effect sits on the surface. It shifts as you change your viewing angle, like a soap bubble or a beetle's shell.
  • Look through one and the view stays mostly clear, with a metallic sheen.
  • Stack two together and you get... two shiny cubes. The colours don't combine.

The CMY Cube

Mixes colour by subtraction.

  • The colour lives inside the material itself: translucent cyan, magenta, and yellow, the three subtractive primaries.
  • Look through any face and the world is tinted in that colour. Light passes through; nothing is mirrored away.
  • Where two faces overlap, they mix into new colours: cyan and yellow make green, magenta and yellow make red, all three make deep darkness.
  • Rotate it and the combinations keep changing. That's real subtractive colour mixing, the same physics behind every printed photo you've ever seen.
The Science Bit

Splitting light vs mixing colour

A dichroic coating works by interference: microscopically thin layers reflect certain wavelengths and transmit others, which is why the colours dance across the surface but never blend. It's beautiful, and it's also fundamentally decorative; the glass itself is colourless.

A CMY Cube works by subtraction. Each face removes part of the visible spectrum from the light passing through it. Overlap cyan and magenta, and together they subtract everything except blue. Layer all three primaries and they can produce every colour your eyes can see, or remove the light entirely. The cube isn't showing you a colourful surface. It's letting you hold colour theory in your hands.

Side by side comparison of a dichroic cube and a genuine CMY Cube
Myth Bust

"You can find one of these inside an old TV!"

We see this comment a lot, and here's the fun part: it's half true. Old projection TVs and projectors really do contain a small glass cube called an X-cube. It's a dichroic prism whose job is to split light into red, green, and blue, then recombine it to build the picture on your screen. Pull one out and you've salvaged a genuinely clever piece of optics. Hats off.

But it isn't a CMY Cube. The X-cube is colourless glass with mirror coatings that split light apart. A CMY Cube is the opposite idea: translucent cyan, magenta, and yellow faces that mix colour together through subtraction, something no TV prism can do. Hold one of each up to a window and the difference is obvious in about two seconds.

So if someone tells you they've "had one for years from a TV," they've got a lovely bit of projector history. The CMY Cube is our original creation, and the only place it's ever lived is in our workshop and your hands.

Buying Elsewhere?

How to spot a genuine CMY Cube

Some sellers use our videos and photos to advertise dichroic or undersized replicas. If you're shopping anywhere other than cmycubes.com or our authorised retailers, check these four things:

  1. Look through it, not at it. A genuine CMY Cube tints your view in cyan, magenta, or yellow. If the colour only shimmers on the surface, it's dichroic.
  2. Check the colours mix. Two overlapping faces should create a brand new colour. Mirrored shine doesn't mix.
  3. Check the size and weight. Replica ads often deliver tiny 1cm cubes. Our Original Cube starts at a satisfying handful, diamond polished until optically clear.
  4. Check the seller. The CMY Cubes name and the cube designs are ours. When in doubt, our retailer list shows everyone authorised to sell the real thing.

For the record: dichroic glass is lovely.

This isn't a takedown. Dichroic glass is a gorgeous material with its own century of history in optics and art. But it isn't what we make, and it isn't what our videos show. If you fell in love with the way colours blend, shift, and bloom through a translucent cube, only subtractive colour mixing does that. Accept no shiny substitutes.

See the real thing for yourself.

The Original Cube, diamond polished and optically clear, straight from the people who created it.

SHOP THE ORIGINAL CUBE