Okay, so I've made a cake that is ivory fondant. That part is fine. I've attached light purple fondant diamonds to the cake. Only now they turned blue. The really sad part is, it's the second time it's done this. Technically, they are cake dummies. Made the first one and it dried all weird and had to redo it.

What causes this? Any suggestions? Anything I can do to save the one I have (it really needs to be light purple and not blue) or anything to keep it from happening again?

TIA,
Suz

For some reason the purple or violet colors always seem to do this and I'm not sure why! My mom did my wedding cake in Lavender basketweave and it turned a bluish/grey but still looked nice.

Violet or purple and pink are very much affected by light and must be kept out of both daylight and artificial light sources. Blues and other colours can also be affected.
Also some fondants, like McCall's for example, containe yellow oxide. This creates issues when you are colouring the fondant and when it dries. Fondant covered cakes can keep indefinitely if kept out of the light and are not in a smoking envioronment. Humidity also affects them.
Hope that helps,
Hugs Squirrelly

Is this only on fondant that it will happen with these colors or on buttercream as well?

How about on MMF?

No this has happened to BC as well.My wedding cake was Buttercream!!

I used Satin Ice.

Anyway, so what do you do? I mean you can't make a cake and keep it in a darkroom. LOL!

This is not good. Guess my partner and I will have to change our "color" to something else, hehe. Our signature cake cannot be blue. ARGH!

Thanks, squirrley! At least I know it's not something I "did" to cause this.

Any suggestions?

Haha, well you don't need to keep it in a darkroom at the reception kiddo, just not in front of a window with sunlight streaming in on it and not under a huge light. But if you can box your cakes up, the light won't get to them. It takes a several hours of light to have this effect and florescent lighting can be even worse. Not sure if you are using the Wilton colours, but they are supposedly worse for this problem so maybe switch to America colours. Also, is the fondant you are colouring already ivory or are you starting with white fondant? You need to start with white fondant in this particular case. Most ivory fondants do have the yellow oxide or other colour additives that will make this more of an issue.
I use big moving boxes to box wedding cakes, just cut down one section and tape it up after the cake is inside.
Hugs Squirrelly

Ahhhh, I see. Thank you so much. I was using the leftover ivory fondant and coloring it. Okay, so no more Wilton, white fondant and get the whole thing somewhere darker, or in a box. Great, I think I have it!

You're the best!

If you PM Colorboy about it, he posted something a while ago... the pigments that make the violet colours are not very stable in general, but he claims that the Americolor brand encapsulates the pigments somehow (don't know the details) which helps.