The general size depends on the height and thinness of the person wearing it. Women who are taller and fatter usually wear 10- 12 mm, and those who are shorter and thinner wear 6-8 mm. For men, women who are taller and fatter usually wear 16- 18mm and those who are thinner wear12-/kloc-0.
Amethyst is the lucky stone of Aquarius, which can stabilize mood and improve inspiration. If it's not too weak, you can wear it.
Blonde hair is more suitable for people with weak personality, which can increase self-confidence and determination, but it is not suitable for people with strong and irritable personality, which will aggravate these situations.
Crystals suitable for people with strong personality and bad temper: pink crystal (to relieve impatience), amethyst (to stabilize mood), moonstone (to help lose weight with pink crystal), agate (to make people stable and gentle), topaz (to make people cheerful and happy, to help lose weight), strawberry crystal (to make people positive and optimistic) and tea crystal (to stabilize the gas field and make people practical).