Tourmaline's three-six-ninth, etc.

Colored gems are graded by color, and tourmalines are no exception. The most demanding colors in the tourmaline market are pink, bright red and green, with red and green tourmalines being the most common and popular.

However, only moderately medium and vivi.......

[Commonly Used Textiles Manual]

Overview
The worsted fabric used to make umbrellas and tents. Requires tight fabric structure, good water repellency, good elasticity, strong wrinkle resistance, and moderate stiffness, so as to facilitate the opening and cl.......