Topics: Knotting to Protect Soft Stones and Pearls
I've noticed that for some beads such as natural pearls and malachite, it's recommended that they be strung on silk or similar with knots between beads to protect them, while other beads such as amethyst and crystals can be strung touching each other on something like Accu-Flex® beading wire. Is there an easy way to determine which beads should be strung and knotted on silk, and which ones will be okay strung on metal?
The recommendations you're seeing are based on the hardness of the stones. Softer materials, such as malachite and cultured freshwater pearls, are so soft, in fact, that they can be scratched by a coin! This type of gemstone characteristic can be found in the ''Mohs Scale of Hardness'' chart. The Mohs hardness scale measures the hardness of gemstones on a scale of 1 to 10, as determined by their scratch hardness.
Knotting between softer gemstone materials prevents them from scratching each other. You can also string them on nylon-coated, Accu-Flex. You'll want to use a seed bead or another type of smooth-profile bead between the stones to protect them.