Gemstone from Synth Use?

Hi everyone.

Im just wondering how to use or what is the use of the gemstones you can get from guild maze or synthesis npc.
For example, I got diamond gemstone from guild maze and it says "for color change".

I hope somebody can answer my question. Thanks!

 

It's a item u need for changing ur character's hair or eye color, u change it under the change character page, just press the char ur currently using and a "change appearance " option will be there.
If u don't have the necessary materials for the look or color u want u can just use orbs instead.

 

i see. thanks you!