What Is a Blemish in a Diamond?
Key Takeaways
- Even the most exquisitely cut diamonds can still have "blemishes." This condition is called Blemish. To better understand what a diamond blemish is and how it affects the value of a diamond,...
Even the most exquisitely cut diamonds can still have "blemishes." This condition is called Blemish. To better understand what a diamond blemish is and how it affects the value of a diamond, join Jemmia Diamond in exploring it more deeply in the article below.
What is Blemish in diamonds?
Blemish refers to defects or flaws that appear only on the surface of a diamond. These flaws may be scratches, small cracks, cloudy patches, or foreign substances clinging to the surface, affecting the stone’s brilliance and value.
Diamond blemishes are formed due to errors during the crafting process, or from wear and tear caused by improper use and storage. According to GIA (Gemological Institute of America), Blemish is indicated by green or black symbols on the grading diagram, helping buyers easily identify these characteristics.
Blemish refers to defects or flaws that appear only on the surface of a diamond
Common types of Blemish
Some common types of diamond blemishes include:
- Abrasion: Small scratches along the edges.
- Extra Facet: A facet that does not follow the standard cutting style.
- Lizard Skin: A rough, uneven surface.
- Natural: A remaining portion of the original rough diamond surface.
- Nick: A small notch on the junction edge.
- Pit: A tiny hole resembling a white dot.
- Polish Lines: Faint groove lines caused by polishing.
- Burn Mark: A cloudy surface caused by high temperature.
- Rough Girdle: An uneven, granular girdle.
- Scratch: A thin, faint line on the surface.
- Surface Graining: Wavy lines caused by abnormal crystal structure.
Common types of Blemish
How does Blemish affect diamond quality?
Blemish affects many aspects of a diamond, specifically:
- Impact on Clarity: Large or too many blemishes can lower a diamond’s clarity grade, making it appear less perfect.
- Impact on appearance: Scratches, cloudy patches, burn marks, or other types of surface diamond blemishes can make the diamond look less sparkling, less bright, or have distracting spots.
- Impact on value and investment: Diamonds with few or no blemishes are considered high quality, so their market price is also higher. They are also the preferred choice for investment purposes, because the fewer blemishes a diamond has, the better it retains value and the higher its liquidity.
Blemish can greatly affect the value of a diamond
Comparing diamond Blemish and Inclusion?
To better understand diamond quality and value, buyers need to know how to distinguish between blemishes and inclusions. Below is a detailed comparison table of diamond blemishes and inclusions:
Comparison criteria | Blemish | Inclusion |
Nature | These are defects or flaws in the crystal structure of the diamond. | These are characteristics or materials located inside |
Position | Appear on the outer surface of the diamond. | Located inside the diamond. |
Cause of formation | Usually caused by the cutting, polishing, treatment process, or by wear during use. | Formed naturally during the diamond’s growth process underground. |
Typical examples | Scratch, burn mark, abrasion, lizard skin, polish lines, natural, small hole. | Foreign crystal, feather crack, cloud, needle, twinning, cavity. |
Removability/Alteration | Some small blemishes can be removed or minimized through repolishing | Cannot be removed or changed without recutting the diamond (which reduces weight). |
Effect on clarity | Does affect the Clarity grade, especially if large or too numerous, but usually less than an Inclusion of the same size. | Directly and strongly affects the Clarity grade, and is the main factor determining clarity. |
Effect on durability | Usually has little direct impact on durability, unless it is a deep crack or a large chip. | Some large inclusions, located near the surface or in stressed areas, can affect a diamond’s durability. |
Learn more: What are diamond inclusions? Do inclusions affect value & durability
How to check for Blemish when buying diamonds
When buying diamonds, buyers can ask the seller to allow you to inspect diamond blemishes in order to choose a stone that suits your preferences with appropriate quality and value. Below are the steps you should take:
- Use a specialized magnifying loupe (10x Loupe) to enlarge and clearly see small diamond blemishes that cannot be seen with the naked eye.
- Use balanced white light that is not too harsh for the clearest observation. Avoid lighting that is too strong or too weak, as it can obscure cloudy spots or scratches.
- Check each area of the diamond such as the table, crown, pavilion, and girdle to inspect for scratches, abrasions, cracks, or burn marks on the facets. You should also rotate the diamond to inspect it from different angles, because some blemishes are only clearly visible under certain lighting or viewing angles.
- Request to see the diamond’s grading report to clearly understand the characteristics and positions of the diamond’s blemishes and inclusions, helping you compare and verify them.
- Observe whether the blemish affects the diamond’s brilliance and sparkle.
- Consult an expert if you are unsure about diamond blemishes.
Diamond blemishes are understood as surface defects that affect the quality and value of a diamond. Therefore, when you need to buy diamonds, you should clearly understand the types of blemishes in order to choose high-quality jewelry.
