Opals and body heat

Does anyone happen to know if opals react to body heat?

I know they can explode if they are in contact with a lot of heat, but my birthday opal ring arrived just plain white but the more I've been wearing it, the more slivers of colour have started appearing!

I love my 3 opal rings but the one I got for my birthday is huge and the colours are more obviously appearing the more I wear it!

If you know or have an opinion about it, please leave me a comment?