In short: A fracture filled diamond has had surface reaching cracks filled with a glass like substance to make them less visible. It can make a stone look cleaner than it really is, but the treatment is not permanent and can be damaged by heat or harsh cleaning. The simplest way to avoid one is to buy a diamond with a grading report from GIA or IGI and to ask the seller directly whether the stone has been treated.
What Is a Fracture Filled Diamond?
Many natural diamonds contain small fractures, sometimes called feathers, that reach the surface of the stone. When light hits these fractures they can look white or reflective, which makes the diamond appear less clean.
Fracture filling is a treatment designed to hide them. A filler, usually a lead based glass, is introduced into the fractures under controlled conditions. Because the filler bends light in a similar way to diamond, the fractures become much harder to see. The result is a stone that looks as if it has a better clarity grade than it really does.
The treatment only works on fractures that reach the surface, because the filler has to get in from the outside. Inclusions that are fully enclosed inside the stone cannot be filled.
Why It Matters
Fracture filling is not illegal, and a filled diamond is still a diamond. The concerns are about durability, value and disclosure.
Durability
The filler is far softer than diamond and it is not permanent. It can be damaged by:
- Heat. A jeweller's torch used during resizing or repairs can cause the filler to bubble, cloud or come out.
- Ultrasonic and steam cleaning, which are commonly used in jewellery workshops.
- Some chemicals and acids.
If the filler is damaged, the fractures can become visible again, and the stone may look worse than it did before treatment. This makes future repairs or resizing more complicated, because the jeweller needs to know about the treatment in advance.
Value
A fracture filled diamond is generally worth considerably less than an untreated diamond that looks similar, because its apparent clarity comes from the treatment rather than the stone itself. Paying an untreated price for a treated stone is the real risk.
Disclosure
Reputable sellers disclose treatments. The problem arises when a filled stone is sold without that information, for example through private sales or listings that give no grading report.
How Grading Laboratories Treat Filled Diamonds
GIA does not issue its standard grading report for fracture filled diamonds, because the filler would make a clarity grade misleading. If GIA identifies filling, it will say so rather than grade the stone in the usual way. Other laboratories may grade treated stones but note the treatment on the report.
This is one of the main reasons to buy a diamond with a report from a respected laboratory. At À Vie Diamonds we work with GIA or IGI certified stones, and we tell you about every relevant detail on the report before you choose.
How to Spot a Fracture Filled Diamond
Identifying filling with certainty is a job for a trained gemmologist or a laboratory. That said, there are signs a jeweller looks for under magnification:
- The flash effect. As the stone is tilted, a filled fracture can show a flash of colour, often orange, pink, blue or green, that changes as the viewing angle changes. This is the most well known sign.
- Trapped bubbles or a slightly cloudy texture within the fracture.
- Flow lines, which can look like faint streaks where the filler has moved through the crack.
- A clarity that seems too good for the price. Not a test in itself, but a reason to ask more questions.
Do not rely on spotting these yourself through photos. A clear grading report and an honest answer from the seller are far more reliable.
Fracture Filling and Other Diamond Treatments
Fracture filling is one of several treatments used on diamonds. Others include laser drilling, which creates a tiny channel to reach a dark inclusion so it can be lightened, and treatments that change a diamond's colour. Each has a different effect on appearance and durability. The common thread is the same: treatments should be disclosed, and a reputable grading report is the best way to know what you are buying.
How to Avoid Buying One by Mistake
- Insist on a grading report from a respected laboratory such as GIA or IGI, and check that the report number matches the stone. Many certified diamonds have the report number laser inscribed on the girdle.
- Read the report fully, including any comments section, where treatments are noted.
- Ask directly: "Has this diamond been treated in any way?" A reputable jeweller will give you a clear answer.
- Be wary of unusually low prices for a stone with high apparent clarity, especially without a report.
- Get a second opinion from an independent gemmologist if you are buying privately or second hand.
Questions to Ask Before You Buy
Whether you are buying a loose diamond or a finished ring, a few questions will tell you a lot about the seller as well as the stone. Ask which laboratory graded the diamond and whether you can see the full report. Ask whether the stone has had any treatment of any kind. Ask whether the report number is inscribed on the girdle and whether you can check it. A seller who answers clearly and in writing is one you can trust with a purchase of this size.
What If You Already Own One?
If you know or suspect your diamond has been filled, there is no need to panic. Many filled diamonds are worn for years without trouble. The key is to tell any jeweller about the treatment before cleaning, resizing or repair work, so they can avoid heat near the stone and skip ultrasonic or steam cleaning. Gentle cleaning with warm water, mild soap and a soft brush is the safest approach at home.
A Clearer Alternative
If your aim is a clean looking diamond within a set budget, there are better routes than treatment. You can choose a lower clarity grade where inclusions are not visible to the eye, or consider a lab-grown diamond, which usually costs considerably less for the same size and grade. Both are explained honestly in our diamond clarity guide, lab-grown diamond guide and natural diamond guide.
When you commission a ring through the bespoke journey, you will see photos and video of certified stone options before you decide, with the report for each one. Get in touch if you would like help comparing stones.
Frequently Asked Questions
Is a fracture filled diamond a real diamond? Yes. It is a real diamond that has been treated to make surface reaching fractures less visible.
Is fracture filling permanent? No. The filler can be damaged by heat, ultrasonic or steam cleaning and some chemicals, which may make the fractures visible again.
Does GIA grade fracture filled diamonds? GIA does not issue its standard grading report for fracture filled diamonds and will identify the treatment instead.
How can I tell if my diamond is fracture filled? A gemmologist can look for signs such as the flash effect under magnification. A laboratory report gives the most reliable answer.
Are your diamonds treated? Every centre stone we supply comes with a GIA or IGI report, and we go through the report with you before you choose.