Gems - purple stats

Hey guys,

Can someone explain as I can't seem to find any info on it -

Some gems have purple colored stats like in the pictures, some have not at all and some gems have all purple stats - what does the purple color mean on a gem compared to the blue ones?

https://preview.redd.it/oa6ntewfn60f1.png?width=577&format=png&auto=webp&s=cbd85a5be1738a2c6219bce53c42fa8aa19ac873

https://preview.redd.it/2wafvzzin60f1.png?width=536&format=png&auto=webp&s=046fca77bed91aec48400a60031bd957b0d517a1