This guide may help you to determine the gemstones that you come across:
Sometimes you can see where a tint has not absorbed fully into the gemstone.
There are many gemstone dealers using words like 'Jade', 'Amazonite', etc. to refer to certain colours. Among those we've come across are gemstones called 'Olive Jade' or 'Purple Jade', and whilst these names are authentic, the gemstones you might come across may have been tinted.
The banding in gemstones are typical in some agates. Carnelian is known for its deep orange/red colour, but can also be opaque grey/brown. Sometimes they are 'colour washed'.
Price is often a good indicator of a gemstone's authenticity. if it seems to good to be true, it probably is.
From a design perspective:
Colour is GOOD
Colour is DESIGN
Colour can be express MOOD or EMOTION
Colour is CRAFT
Do you know which crystal this is? Discuss in your group/s