Black Diamond apples (Gala guo)

Black Diamond apples are grown in Nyingchi, Tibet as a rare variety of Hua Niu apples (Chinese Red Delicious). Although they're called black, the skin of these apples is actually a dark hue of purple because they receive lots of ultraviolet light during the day and the temperature changes dramatically at night.

On the inside, the pulp is bright and white just like most other apples. Due to the fact that the production is limited, the apples are quite pricey and belong to the high-end segment of the market. The flavor of Black Diamond apples is said to be much sweeter than the flavor of other apples as they're full of glucose.

And hurry up while you can still find them – many farmers are refusing to grow them any longer because these apple trees require 8 years to reach maturity.