Because of turquoise's soft and porous nature, ultrasonic cleaners and steam cleaners should never be used to clean turquoise jewellery. The gem should be cleaned with a soft, dampened cloth.Turquoise beads may darken over time if they are in direct contact with skin.
Natural, untreated turquoise with a bright luster and deep, blue homogenous colour - and no matrix veining is also highly collectible. The same holds true with turquoise that has known provenance.
"Spiderweb" matrix, containing fine dark lines with an attractive, even pattern surrounded by deep blue turquoise is preferred by some collectors. While turquoise from Persia (Iran) was a long a standard for the finest turquoise, material from the United States - specifically Arizona has proven to be of equal or greater quality in some cases.