Diamond is the hardest material on earth, though that doesn’t mean it can’t be scratched (for example by another diamond). Since diamond is brittle (it can shatter fairly easily under impact), it’s also possible to cause fractures or chips in a diamond.
A scratched diamond can be fixed to remove the appearance of the scratch. This process however will involve removing a certain weight of carats and needs to be carried out by an expert to reduce the risk of further damage or shattering the diamond.
There are different options available for potentially fixing a scratched diamond, though which one is best will depend on the degree of damage, whether the diamond is suitable for repair, and how cost-effective it may be to repair it.
Hardness versus toughness
Diamond is well known as the hardest natural material on the planet. It has a value of 10 on the Mohs scale, which is a scale used to measure the hardness of minerals.
It’s useful to determine what hardness means in this context, as it’s not the same as toughness. Hardness refers to the ability of a material to resist scratching.
Toughness however refers to the ability of a material to resist breaking. While diamond sits right at the top of the Mohs scale with exceptional hardness, it’s not a particularly tough material and can fracture or shatter with sufficient force applied to it.
The brittle nature of diamond means that any repairs to remove scratches or other damage need to be carefully considered and carried out by an expert,
Minor repairs through polishing
If a diamond has a small amount of damage such as a small scratch or chip, it’s possible to repair the damage by getting it professionally repolished. However, it’s important to note that repolishing won’t replace missing parts of the diamond to fix the damage.
Rather, the process involves reducing the diamond’s carat weight to create a smooth surface once again. While this sounds like it could greatly reduce the value, usually only a small loss of carats is involved (around 0.02 to 0.1 carats) to complete the job.
Sometimes however the damage is too large to be fixed through repolishing and may require recutting the diamond to remove the damage.
Large repairs through recutting the diamond
Most surface scratches are unlikely to require the diamond to be recut to remove them. However, if the scratch is particularly large or deep or has resulted in fractures or chips, recutting may be required to remove the visible damage.
Such an option needs to be carefully considered, as this will involve removing more of the diamond than simply repolishing it. A diamond cutter may have to redesign the diamond and removing parts of it in the recutting process could significantly reduce the value of the diamond.
Additionally, there is the risk that the diamond could shatter during the recutting process. Diamonds have cleavage planes, with cleavage referring to how strongly the diamond molecules bind together.
Diamonds have perfect cleavage, which means they split easily along cleavage planes. While useful for cutting them if done correctly, it also increases the chance of a diamond chipping or shattering, either from general wear and tear or during the cutting process.
If the damage is significant, it’s important for a professional cutter to assess whether the diamond is suitable for recutting as some won’t be. It’s also up to the owner to decide whether they want to risk reducing the value of the diamond significantly or risk it shattering.
If too many carats would need to be removed, it may not be cost-effective to repair the damage. However, this is more of a concern for smaller diamonds and not as much of a concern for larger diamonds.
While a recut may sound extreme, sometimes it can result in better clarity, improving the overall appearance of the diamond. If a small number of carats can be lost to obtain a higher clarity rating, it may be a worthwhile trade-off.
If a diamond is scratched, it’s not advisable to leave it in its current state unless it’s safely stored away and not exposed to an increased risk of damage. Repolishing the diamond can be an effective solution to halt further damage if it will be exposed to regular wear and tear (such as within frequently worn jewelry).
Additionally, if the diamond is part of a ring, the owner may be well served having it reset in a bezel setting or alternatively transferred to a necklace where it will experience reduced wear and tear compared to a ring.