Hairline, Cotton Line, Structure Line, and Mineral Line in Jade: What Is the Difference?
Natural jade is not factory-made glass. It formed underground through an extremely long geological history, with pressure, mineral growth, changes in texture, color, and structure. Those little lines can be part of that history.
|
One important thing before we start |
What Do They Have in Common?
1. They can all be visible
Some are easy to see in normal lighting. Others may only show under strong light, , close-up photography, or a very specific angle. A line can look almost invisible on the wrist and suddenly become obvious under a flashlight.
2. Normally, you should not be able to feel them
In most cases, these features are internal and the polished surface stays smooth. Your finger or fingernail normally should not catch on the line. There can be exceptions: if two mineral or structural areas have a noticeable difference in texture or hardness, polishing can leave a very slight surface texture. That does not automatically mean the jade is cracked.
3. They normally do not affect the firmness of the piece
Hairlines, cotton lines, structure lines, and mineral lines are generally stable natural features and do not normally affect everyday wear ability. This is different from an open or incompletely healed crack, especially one that can be felt on the surface or runs deeply through the jade.
4. The name is not always absolute
Natural jade does not organize itself into perfect textbook categories. A structure boundary can contain cotton. A mineral seam can also look like a structure line. A healed hairline can contain later mineral growth. So sometimes one person may call a line a hairline while another calls it a cotton line or structure line — and both may be looking at the same natural feature from a different point of view.
Quick Comparison
|
Feature |
A simple way to think about it |
Usually visible? |
Usually felt? |
Normal firmness |
|
Hairline |
The “scar” of the stone — a fine trace of an old separation that naturally healed and fused together |
Yes |
No |
Usually unaffected |
|
Cotton line |
Cotton-like, cloudy internal material concentrated into a line |
Yes |
Usually no* |
Unaffected |
|
Structure line |
A boundary between areas with different internal structure, grain, texture, color, or translucency |
Yes |
No |
Unaffected |
|
Mineral line |
A natural seam or line created by a different mineral or mineral-rich area |
Yes |
Usually no* |
Unaffected |
|
Crack |
An open or incompletely healed separation in the stone |
Yes |
yes |
Depends |
*A mineral or structural line may occasionally have a slight surface texture if the
Example
Hairline
Cotton line
Structure line
Mineral line
