The September birthstone is Sapphire. Originated from the Greek ζαφείρι, which means blue.

Medieval European nobles regarded Sapphire as a testimony of love. They believed that if the person is not chaste and received the sapphire, the gem would lose its brilliance. Thus, men give sapphires to their lovers to test whether their loved ones still be faithful. Ladies also wear sapphires to show their loyalty, forming the custom of using sapphires as a token of love.

In 1981, Prince Charles also chose sapphire for his wedding ring when he proposed to Princess Diana, which means loyalty, constancy, love and honesty.

Sapphire is blue because of the trace elements such as iron and titanium.

The "Cornflower Sapphire" from Kashmir is the best among sapphires. Burmese sapphire is strongly dichroic, and blue-green can often be seen on the side. Sri Lanka's sapphire has high transparency and with clear colour band. The Sapphire in Thailand is excluded from fine jewellery since its colour is too dark.

Apart from the colour, clarity, cut, weight, etc., the buyers will also consider whether it has been optimized by heat treatment. Since the price difference between the two will be huge.

Other Sharing of Collection: Vivianite 

Vivianite is a rare and beautiful hydrated iron-bearing phosphate mineral found in many geological settings. The vivianite crystals belong to the monoclinic system. It is blue, green in appearance or colorless transparent crystal with vitreous luster, a set of fine cleavage and fibrous fractures. Streaks are white or blue-green and crystals can be cut or bent. 

The pure vivianite is colorless, but easily oxidized and discolored. The vivianite crystals are mostly long columnar, transparent when fresh. Long-term exposure to light will gradually make them darken, turn green or even black. The perfect crystals are rare and often fill cavities in fossils. In order to maintain the beautiful blue-green color of the vivianite, it should be kept out of sunlight or kept in a dark storage cabinet.