Formal, jewelry (craft) "long", that is, hard and wear-resistant, can last for a long time. Because of its high value, people must expect it to be durable, valuable and even heritable. One of the reasons why diamond is the most expensive gem is that it is the hardest in the world and is not afraid of corrosion. Therefore, most of the high-value gems in the world are silicate minerals with high hardness and corrosion resistance (such as jadeite), a few oxides (such as rubies and sapphires) and elemental minerals (such as diamonds), while the soft and corrosive gems (such as xiuyan jade and Southern Jade) are of higher value. But there are also a few precious stones that are not included, such as opals and pearls. "Sparse" means less output. Rare things are precious. Emerald, which is extremely rare in the world, is of high quality and worth tens of thousands of dollars (.2g) per carat. However, some beautiful and "lasting" gemstones (such as amethyst) have always been low in price because of their large output and easy mining. Some ordinary rocks, after pondering, also have the characteristics of beauty and durability, but they cannot become a member of the gem family. The reason is that things that are easy to get will be cheap.

Generally speaking, jewelry, handicrafts or other treasures made of natural materials (minerals, rocks, organisms, etc.). ) gold and silver and items with certain value are collectively referred to as jewelry, so there is a saying of "gold and silver jewelry", and jewelry stores that operate these items are also collectively referred to as "jewelry stores". Scientifically speaking, the concept of "jewelry" is the same as "gem" in a broad sense. Gems in a broad sense generally refer to those raw materials suitable for polishing or carving into jewelry or handicrafts.

Gems must have the following characteristics: "beauty", that is, gorgeous, crystal clear and dazzling. If a gem is not beautiful, it can't be a gem, and this beauty may be manifested in gorgeous colors.

Girma jewelry is transparent and clean, or has special optical effects (such as cat's eye, discoloration and luminescence), or special patterns (such as chrysanthemum stone, agate and plum blossom jade). For example, diamonds with few defects can be polished into precious diamonds, while those with poor transparency, many defects and black color can only be used as industrial raw materials.