How to evaluate the value of pearl?

There is no international standard for grading pearls jewelry; there is a system that is commonly used to evaluate these beautiful colored gemstones. Developed by the Gemological Institute of America (GIA), the world's largest non-profit institute of gemological research and learning, this grading system considers seven pearl traits when determining value. They are: size, shape, color, luster, surface quality, nacre quality, and matching. Before trying to evaluate a pearl, you should know what type of pearls it is. Each type has its own characteristics due to the specific forming condition. We normally classify pearls by origin, and then grade them within the types they subjected to by the seven facts. Because they are produced in different animals in different environments under unique conditions, each pearl type has its own expected characteristics. When the traits shown for a certain pearl are outside the norm for its type, the pearl will be more valuable. Each pearl is unique, and uniquely beautiful. Which pearl and pearl type is the most beautiful? It's up to you. Maybe a pearl necklace sent by your lover is a precious present that can not be counted by its value.