Sheep Fat White Jade Appreciation Points:
Sheep fat white jade is considered the highest quality of Hetian jade, known for its purest white color and superior luster and texture. It has a warm, firm, and flawless appearance, resembling gelatin in its smoothness. According to Yan Yixuan, one of the simplest ways to distinguish sheep fat jade from ordinary white jade is by observing it under a white fluorescent lamp.
When exposed to a fluorescent light, sheep fat white jade appears as a pure white, translucent material with a soft, powdery glow. In contrast, regular white jade may appear translucent but lacks that powdery sensation. The key difference lies in the fact that while all white jade may look very white to the naked eye, it will usually show a slight yellow tint under a fluorescent lamp. If there’s any yellowish hue visible, it cannot be classified as true sheep fat white jade. Genuine sheep fat jade that meets strict standards is often subtle and not immediately obvious. To identify authentic sheep fat jade, five criteria must be met: pure texture, fine structure, good water clarity, oily white color, and heavy, oil-like weight.
Pure Texture – Sheep fat jade contains up to 99% tremolite minerals. It is found in the most perfect part of wall rock alteration. When granodiorite comes into contact with dolomite, a series of contact metamorphic rocks are formed, turning dolomite into marble. Later magmatic hydrothermal fluids move through tectonic fissures in the marble, forming tremolite. This process results in three types of lithofacies: dolomite marble, tunnelized petrochemical dolomite marble, and metamorphic rock, with sheep fat jade occurring in the tremolite rock facies.
Fine Structure – The tremolite in sheep fat jade is microcrystalline and aggregated. Under an electron or optical microscope, the tremolite fibers measure approximately 0.033–0.01 mm in length and 0.0006–0.001 mm in width. These microscopic, fluffy, felt-like crystals intertwine to form a pile-like, felt-like, or interwoven structure. Under polarized light, they do not exhibit uniform extinction at the same angle, which is a distinguishing feature.
Water Head – Water head refers to the transparency of jade. In tremolite jade, a thickness of 2mm is typically used as the standard. At this thickness, white jade is usually translucent to opaque, while sheep fat jade remains translucent, showing a clear and bright appearance.
Color – Sheep fat white is not just pure white; it has a soft, oily sheen. Some pieces may show a slight yellow tone, and lower-quality ones might even have a faint grayish tint. However, the best examples maintain a clean, elegant white with a subtle luster.
Oily Weight – When handled regularly, sheep fat jade feels smooth and oily on the surface, giving a unique tactile experience. Even when submerged in water, it can drip without sticking, showcasing its high density and toughness. This “oily weight†is a key characteristic of high-quality sheep fat jade. Only jade meeting all five criteria can be considered the finest. The Yangyu White Jade from Shanghai Yufu Workshop combines all these qualities, making it one of the most highly regarded jades in the world.
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