Rhinestones are man-made imitation gemstones that are used to decorate clothes and jewelry. They are made from various materials such as rock crystal, crystal glass, or polymers like acrylic. Rhinestones can be used as imitations of diamonds, and some manufacturers even manage to partially reproduce the glistening effect that real diamonds have in the sun. Here are some key facts about rhinestones:

• Rhinestones were originally small, sparkling quartz stones found in the Rhine River in Austria in the 13th century.
• The name "rhinestone" comes from the discovery of crystals that were gathered from the Rhine River.
• The highest quality rhinestones have been made from leaded crystal, which is glass to which other ingredients, such as lead, have been added, creating a material that is easier to cut and refracts incoming light.
• Rhinestones can be made from various materials such as crystal, glass, or even plastic acrylic.
• Crystal rhinestones are produced mainly in Austria by Swarovski and in the Czech Republic by Preciosa and a few other glassworks in northern Bohemia.
• Plastic rhinestones are also called "plastic gems" and "imitation stones". They are mass-produced, low-cost, lead-free, light, and do not easily break.
• Rhinestones can be used to add sparkle to accessories such as jewelry, bags, or apparel.

In summary, rhinestones are man-made imitation gemstones that are used to decorate clothes and jewelry. They can be made from various materials such as crystal, glass, or plastic acrylic, and are produced mainly in Austria and the Czech Republic.