I heard somewhere that the WCA won't let you use colored cubes (meaning cubes that have different colored plastic). This can't be good since my best speedcube is an orange GH2 that I've put a lot of work into making it near-perfect...

Can anyone shed some light on this? Is it true or just a rumour?

--JC--

Cubes that use multicolored plastic are not allowed because you can see more of the puzzle than with normal stickers (do a 45 degree turn on the back layer and you can see the colors of the edges). However, a cube that is any color solid plastic is perfectly fine. Whether it is black, white, pink or even orange.

I think they are allowed. That is of course if you are talking about a solid colored cube with stickers, not a cube with colored plastic replacing stickers.

Here are the official rules for puzzles: http://worldcubeassociation.org/regulations/#puzzles

3a) Competitors must bring and use their own puzzles. Competitors may borrow puzzles from other competitors, although both competitors must be ready to compete when they are called for to do so.
3b) Puzzles must be in reasonable working order, so that normal scrambling is possible.
3c) Competitors must use any colour scheme for cube puzzles, as long as the puzzles show one colour per face in solved state. For other puzzles competitors must use any variation that has the same moves, positions and solutions as the original puzzle.
3d) Puzzles must either have coloured stickers, coloured tiles, textures or painted colours.
3d1) Puzzles using textures must have different colours on each face to aid in scrambling and judging.
3e) The colours of puzzles must be solid, the same per colour, and clearly distinct from other colours.

3e1) The stickers/tiles/textures/paint may show an image (in one colour), as long as all stickers/tiles/textures/paint of a colour have the image and the same image.

3f) Stickers/tiles/textures/paint must not be thicker than 1.5 mm, or the generally available thickness for non cube puzzles.
3g) Puzzles may be made smoother internally by sanding or using any lubricant.
3h) No modifications are allowed that enhance the basic concept of a puzzle. Some examples of enhancing the basic concept are: new moves are possible, normal moves are impossible, more pieces are visible, colours on the backside of the puzzle are visible, moves are done automatically, more or other solved states.
3i) Any modifications to a puzzle that result in poor performance or results by a competitor are not grounds for additional attempts in an event.
3j) Puzzles must be clean and must not have any markings, elevated pieces, damages, or other differences that distinguish one piece from a similar piece.
3k) Puzzles must be approved by a judge before use in the competition.
3l) Cube puzzles must have at most one logo. For Rubik's Cube or bigger cube puzzles the logo must be placed on one of the centre pieces.

3l1) Colourless logos (max. 1 logo per colour) that are engraved are not considered as logos.

3m) All puzzle and puzzle part brands are allowed, as long as the puzzles comply with the other WCA regulations.

Some of those sound a bit silly, but this isn't really the place to debate them...

Is there any good reason for the logo requirement?

It is not required for a puzzle to have a logo (this is a common misconception). Logos theoretically would allow you some advantage (a logo on a corner would help you identify more quickly which one it is). However, many puzzles ship with logos by default so they are allowed. You can't have multiple logos because you could get an advantage from that (stick a different "logo" on each face) and you also need to place them on a center piece since placing it on a corner or edge might help you.

I don't think they're necessary but I think you can't have more than one.

Edit: Tom beat me to it.

This is not entirely true!
In normal solving events it is not allowed, but it is allowed for:
Blindfold
Multiple Blindfold
Fewest Moves Challenge
But in basic, you are right. For these special events you will not get any advantage from the multicolor plastic cube.


Thats right!

But I think logos are essential for a competitor. But not commercial logos! Custom logos needed to distinguish the identical cubes, and prevent to loose your cube at competition. Since I'm competing I have lost 4-6 cubes... And most of the times they where my best cubes. Since I have my own logo, I never lost any of my puzzles in competition.