| Why are some stones worth of the title | | | | Gems may be rare for a variety of reasons. |
| gemstone, while others are just precious stones | | | | Many gems are varieties of common stones, but |
| or even worse rocks? | | | | their exceptional color or clarity determines them |
| Since ancient times, many materials have been | | | | to be rare gemstones. Quartz and feldspar are |
| set in jewelry. Over the centuries though the | | | | stones that make up two-thirds of the Earth's |
| term gemstone has come to mean a naturally | | | | crust in a common gray or cream color. Very little |
| occurring mineral desirable for its beauty, its rarity | | | | quartz is amethyst with its gorgeous purple color |
| and durability. | | | | and little feldspar display rainbow iridescence like |
| Gems are diverse in their beauty. Diamonds have | | | | the labradorite feldspar. A few gem minerals are |
| a fiery brilliance, pearls a soft iridescence and | | | | rare due to occurrence. One such gem is the |
| many gemstones occur in a stunning variety of | | | | diamond, which are 5 grams to every 100 tons of |
| colors. The source of the gemstone's beauty | | | | kimberlite, the host rock. Other gems contain rare |
| though is light. The interactions between the | | | | chemical elements such as beryllium in taaffeite |
| minerals in the gemstone and light cause the | | | | and emerald. In few gems these qualities are |
| intense colors of some stones and the amazing | | | | combined with a very large size. For example the |
| play of colors in others. | | | | Cullinan diamond weighed 3,106 carats in its rough |
| Most gemstones have little beauty in the rough | | | | state. |
| state. They may look like ordinary rocks or | | | | Gems manage to endure through time because |
| pebbles. It is not until a skilled cutting and polishing | | | | they are resistant to chemical alteration, are hard |
| by a lapidary, that the full color and luster of that | | | | enough to retain a good polish and are not easily |
| stone can be seen. This is never more noticeable | | | | chipped or broken. Hardness is the measure of a |
| than in the diamond. The diamond's magnificent | | | | gemstone's resistance to abrasion. To wear well a |
| fire is displayed in a precise cut to show off the | | | | gemstone must be tough. Despite being harder |
| stone's natural inclinations. | | | | than quartz, emerald is brittle and chips easily. |
| The rarity of a stone imparts a sense of | | | | Diamond and topaz break along planes of weak |
| exclusiveness and worth that increases our desire | | | | atomic bonding if dropped or knocked against |
| to possess it. Rarity determines the prices placed | | | | hard objects. |
| on gems and famous jewelry the world over. | | | | |