Ruby is a natural gem with many cracks and inclusions, so the crystal grain of ruby is relatively small and the high quality is very rare, but the market demand for high quality ruby has never declined, but it has been rising. So there is burning, and burning is heating to improve the quality of rubies. Unburned rubies are rubies that have not been heated. According to the survey data, most rubies on the market are burned.

Ruby burning can be divided into two situations: optimization and treatment. Optimization is to improve the color of ruby by simple physical heating, without adding other substances, and there is no residue after firing. This heating method has been recognized by consumers and industries, which is also commonly known as "old burning" and has a high degree of acceptance in the market. Treatment refers to adding other substances during heating. After heating, the substance remains in the gap of the gem, which is called "new burning" in the market. This is not recognized and accepted by the industry and consumers, and it is not recommended to buy this ruby.

Natural unburned ruby represents the high quality of ruby, and the price is naturally much more expensive than burned ruby. If such rubies reach the weight of investment collection rubies, the price will be much higher. At the time of purchase, many people can't and can't tell whether the ruby has been burned. At this time, they can judge according to the certificate of gem identification and testing. However, it is very important to note whether all the jewelry appraisal and testing certificates are marked with whether the gem has been burned or not. There are generally no domestic jewelry appraisal and testing certificates, and only the certificates of international authorities will be marked.