Hematite rings in different sizes.
Hematite is a grounding and protective stone. It protects you from negative energy.
Hematite rings can break when they have absorbed too many negative energy, so it's beneficial to cleanse them once in a while (check the 'About crystals' page for info on cleansing).
Note: It's best to take your hematite ring off when showering, washing your hands, swimming... Hematite can rust when it gets in contact with water too much.
How to measure your ring size: Measure the inside of a ring of yours in mm, you can check which size is similar to your ring :)