GIA Chip Definition: A shallow opening caused by damage to the stone’s surface that typically occurs at a girdle edge, facet junction, or culet.

GIA Gemology Guide: Chip Inclusions in Diamonds

For a GIA student or professional jewelry appraiser, identifying the exact nature of a surface-reaching characteristic is crucial for both clarity grading and assessing the long-term durability of a diamond. A chip is a common clarity characteristic that requires careful observation, as it represents surface damage that can significantly affect a diamond's structural integrity.

1. What is a Chip?

A chip is defined as a shallow opening or break on the external part of the diamond. It typically has a somewhat jagged or uneven edge and lacks the internal "root-like" stress fractures associated with bruises.

How do they form?

Chips are almost entirely the result of accidental impact or mechanical wear. They occur when:

The diamond sustains a hard blow against a surface during daily wear.
Pressure is applied unevenly by a jeweler's tools during the setting process.
The diamond cutter makes an error or applies too much friction during the manufacturing process.

Note: Chips are most commonly found on the most exposed or vulnerable areas of a diamond, specifically the girdle edge, the culet (bottom point), or the facet junctions.

2. How to Plot a Chip (GIA Standards)

When plotting a diamond on a GIA diagram, identifying a chip correctly is vital for documentation. Because a chip breaks into the surface of the stone and removes material, it is treated as an inclusion rather than just a superficial blemish.

Plotting Steps:

Locate the Feature: Examine the diamond closely under 10x magnification. Look along the girdle, culet, and facet junctions for shallow, jagged breaks.
Plot the Symbol: A chip is plotted using a small, slightly curved line, a small "v" shape, or a localized outline that mimics the shape of the break exactly where it occurs on the diamond diagram.
Use Red Ink: Because a true chip breaks through the surface and extends into the stone, it is plotted in red ink to indicate it is an internal characteristic. (Note: Very minor surface abrasions or nicks without measurable depth are considered blemishes and are plotted in green, but a chip is red).
Key to Symbols: Ensure "Chip" is listed in the "Key to Symbols" in its correct hierarchy based on its impact on the overall clarity grade.

3. Chip vs. Similar Characteristics

Differentiating a chip from other surface-reaching characteristics is a common challenge for students:

Chip vs. Bruise: A bruise (plotted as a red X) features tiny, root-like internal feathers radiating inward from the point of impact. A chip is a physical break or missing piece of diamond without those radiating internal stress fractures.
Chip vs. Cavity: A cavity (plotted with a green outline and red fill) is typically a deeper, more angular void left behind when an internal inclusion (like a knot or crystal) falls out during polishing. A chip is shallower and usually the direct result of blunt trauma.
Chip vs. Nick: A nick (plotted in green) is a very minor, localized surface blemish, almost exclusively found on the girdle. A chip is larger, more jagged, and penetrates deeper than a simple nick.

4. Evaluation and Appraisal Considerations

For appraisers and gemologists, a chip is a critical feature to note, especially when evaluating heavily worn estate jewelry or vintage cuts like Old Mine or Old European cut diamonds, which often have chipped culets.

Impact on Clarity Grade: The effect on the clarity grade depends entirely on the size and location of the chip. A microscopic chip on the girdle might keep a diamond in the VS or SI range, but a large, obvious chip could lower the grade into the I (Included) categories.
Durability Risks: A chipped girdle or culet acts as a structural weak point. If the diamond is struck again in the exact same spot, the chip could deepen or spawn feathers, potentially causing the stone to fracture further.
Appraisal Value: Appraisers must thoroughly document chips for condition reporting. A significant chip negatively impacts value. Often, an appraiser will need to calculate the estimated loss of carat weight if the diamond were to be re-polished or re-cut to remove the chip, which directly factors into the replacement value.

Summary for GIA Students

Definition: Shallow break on the surface, usually located at the girdle or culet.
Plotting: A small 'v' or curved shape drawn in Red.
Key Factors: Look for chips on exposed edges. Differentiate them from bruises by verifying the lack of inward-radiating feathers, and from cavities by their shallower, trauma-induced nature.