National Standard Definition and Grading of Hetian Jade and Mutton-Fat White Jade (Summary of 2024 & 2020 Standards)
Source: Based on the 2024 and 2020 Chinese National Standard “Nephrite (Hetian Jade) Grading, Identification and Classification”.
1. Definition of Hetian Jade (Nephrite)
Hetian Jade (Nephrite) is a naturally occurring mineral aggregate valued for its beauty, durability, rarity, and suitability for carving into jewelry and decorative objects. It is primarily composed of tremolite, sometimes with actinolite, and may contain small amounts of calcite, diopside, graphite, pyrite, chromite, magnetite, quartz, serpentine, chlorite, epidote, wollastonite, apatite, garnet, and other minerals.
2. Key Properties and Composition
- Refractive Index: 1.60–1.61
- Density: 2.95 (+0.15 / −0.05)
- Main Mineral: Tremolite Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂
- Structure: Interlocking fibrous, flaky, or scaly aggregates
- Luster: Vitreous to greasy
- Mohs Hardness: 6–6.5
3. White Jade / Green Jade / Brown (Sugar) Jade / Mutton-Fat White Jade
White Jade
Jade with a predominantly white body color, sometimes with slight secondary tones.
Green Jade
Jade ranging from light to dark green, gray-green, bluish-green, or slightly yellowish-green, colored mainly by iron, nickel, or chromium.
Brown (Sugar) Jade
Jade where the brown sugar-like coloration accounts for at least 85% of the material.
Mutton-Fat White Jade
A premium grade of white jade in which color, texture, clarity, and uniformity are all Grade A.
4. White Jade Color Grading
| Color Grade | Rank | Description |
|---|---|---|
| Pure White | A | Clean, true white with no visible tint |
| Fine White | B | Mostly pure white with extremely slight undertone |
| White | C | White with a mild secondary tone |
5. Jade Texture Grading
| Texture Grade | Rank | Visual Characteristics |
|---|---|---|
| Fine | A | Very fine and dense, smooth oily feel, grain structure barely visible under transmitted light |
| Fairly Fine | B | Moderately fine and dense, somewhat oily; grains visible under transmitted light but not under reflected light |
| Average | C | Coarser and less compact, lacks oily feel; grains visible and uneven |
6. Clarity Grading (Inclusions)
| Clarity Grade | Rank | Visual Characteristics |
|---|---|---|
| Clean | A | Only minor pinpoint inclusions, fibrous inclusions, or water lines (natural structural fiber line); little to no effect on appearance |
| Fairly Clean | B | Noticeable pinpoint inclusions, fibrous inclusions, water lines (natural structural fiber line), or minor natural fissures; some impact on appearance |
| Average | C | Obvious and numerous pinpoint inclusions, fibrous inclusions, water lines (natural structural fiber line), foreign mineral inclusions, or natural fissures; clear impact on appearance and durability |
7. Uniformity Grading
| Uniformity Grade | Rank | Visual Characteristics |
|---|---|---|
| Uniform | A | Color and texture consistent; uneven areas under 5% |
| Fairly Uniform | B | Mostly uniform; uneven areas between 5%–20% |
| Average | C | Clearly uneven; uneven areas exceed 20% |
8. FAQ
Is Mutton-Fat White Jade judged only by how white it is?
No. It must reach Grade A in color, texture, clarity, and uniformity.
What is the difference between White Jade and Mutton-Fat White Jade?
White Jade is defined mainly by color. Mutton-Fat White Jade is a top-grade White Jade meeting strict standards in all four grading categories.
Why is true Mutton-Fat White Jade rare?
Because natural jade rarely achieves top grades in color, structure, clarity, and uniformity at the same time.
Does a certificate guarantee Mutton-Fat White Jade?
No. Certificates confirm the material, but grading depends on detailed evaluation.
Why can prices vary greatly for jade labeled the same?
Because actual quality differs — color purity, texture, clarity, uniformity, size, and craftsmanship all matter.
Must Mutton-Fat White Jade come from Xinjiang?
No. The standard is based on mineral composition, not strictly origin.
Can grading be judged by eye alone?
Visual observation helps, but accurate grading requires proper conditions and experience.
Does top-grade jade always feel very oily?
An oily texture is common in fine jade, but it must be judged together with overall structure and uniformity.
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