Lapis lazuli, lapis lazuli, hardness 5-6, irreplaceable bright blue, has been used as an ornament since ancient Egypt and has a long history. In modern times, it is also adopted by many high-end watches and jewelry as an indispensable part of artistic expression.

Kyanite, hardness 4-7, this stone can be very similar to sapphire. However, the hardness varies greatly in different directions, which makes machining extremely difficult.