So, lets keep this short. ^-^
This is something, we always use this always, so this is important. One reason, why this is so important, is the Well of Eternity, that lies beneath our beautiful city. It's powers are overwhelming. These powers are beyond comprehension and would crush every being without protection. And these gemstones are this protective force. Of course they don't come without an extra. ;D
Every creature, even those who usually wouldn't possess any powers, such as an ordinary human, are granted the powers of their gemstone.
Orange – You share a special bond with fire
Yellow – You share a special bond with sun
Green – You share a special bond with nature
Blue – You share a special bond with air/ wind
Violet – You share a special bond with lightning/electricity
Pink – You share a special bond colour
Red – You share a special bond with emotions
White – You share a special bond with light
Black – You share a special bond with the shadows/darkness
Brown – You share a special bond with earth
Turquiose – You share a special bond with water
How you interpret all of this is up to you. ;D
Just keep in mind, that it's confusing if you change the colour of the gemstone too often.