There is a variety of apples grown in Tibet which are famous for their deep violet color. They are considered to be one of the most rarest and luxurious types of apples.
The color of these apples is so dark because of the geographical location of the high mountains in the small city of Nyingchi in Tibet. Because of the height where they are grown, they are exposed to high levels of ultraviolet light during day time and low temperatures at night. This sudden shift in the temperature enables it to grow and adapt its unique color on the outside, whereas the inside of the apple is same as the ordinary apples.
These black diamond apples taste sweetest because of their high natural glucose content. It has a thicker skin giving it a shinier outlook and a crunchier bite. Regular apple trees consume 2 to 3 years to mature, while this rare form of apple tree requires 8 years to mature and is harvested in the month of October, and are only available in the market for 2 months.