Watermelon or bi-color tourmaline is a fascinating and visually striking variety of tourmaline, a semi-precious gemstone known for its impressive range of colors. What sets watermelon tourmaline apart is its unique, natural coloration that often resembles the appearance of an actual watermelon. This gemstone typically features a pink or red center with a green outer layer, sometimes separated by a thin white zone, mimicking the rind and flesh of a watermelon. The term "bi-color" refers to the presence of two distinct colors within a single crystal, although watermelon tourmaline can sometimes exhibit more than two hues.

The formation of bi-color tourmaline is a result of complex geological processes that occur deep within the Earth's crust. As the mineral develops, changes in its chemical environment cause variations in color. For watermelon tourmaline, the different colors are the result of varying concentrations of elements such as manganese, which gives it the pink or red hue, and iron, which contributes to the green color. The distinct zones of color are created as the crystal grows, recording the changes in the mineral's environment over time. This natural process results in each piece of watermelon tourmaline being unique, with no two stones exactly alike.

Watermelon tourmaline is highly prized in the world of jewelry and gemstone collecting due to its vibrant colors and natural beauty. It is often cut into slices to showcase its distinctive color pattern, making it a popular choice for pendants, earrings, and other decorative pieces. Beyond its aesthetic appeal, watermelon tourmaline is also believed to possess various metaphysical properties. Many people consider it a stone of balance and harmony, thought to promote emotional healing and bring joy and love to its wearer. Whether appreciated for its visual allure or its purported healing qualities, watermelon tourmaline remains a treasured gem for collectors and enthusiasts alike.