Howlite is often dyed to imitate turquoise. Turquoise made in a laboratory has a very uniform color. Chalky varieties of turquoise are often coated with wax or oil to enhance color - and when treated like this, the color change is not permanent. Turquoise is often fracture sealed. This doesn’t mean that it has fractures, it means that it was sealed with an acrylic resin to enhance it's color, texture, and hardness. Turquoise is somewhat soft so avoid scratches and sharp blows. To be certain and coatings are not removed also avoid hot water and household chemicals.
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