IGI Diamond Certifications Guide

To the untrained eye, lab-grown diamonds can appear similar, making it essential to ensure you're getting the quality you’ve paid for. An IGI certification provides a detailed analysis of your diamond’s characteristics, including its cut, colour, clarity, and carat weight (collectively known as the 4Cs), giving both you and your jeweller complete transparency about its grading.

IGI’s rigorous evaluation process guarantees that your diamond meets the exact standards you selected for your engagement ring, allowing you to buy with confidence.

While not all uncertified diamonds are of low quality, IGI is one of - if not the - most trusted and globally recognised gemological institutions for lab-grown diamonds. Choosing an IGI-certified diamond ensures that you are investing in a high-quality, expertly graded stone that will shine for years to come.

IGI evaluates lab-grown diamonds using the universally recognised 4Cs:

• Carat – Measures the diamond’s weight.
• Colour – Assesses the presence or absence of colour.
• Clarity – Evaluates internal and external imperfections.
• Cut – Determines how well the diamond has been shaped and faceted for optimal brilliance.

To learn more about these factors, explore our in-depth diamond guides.

Polish
Polish refers to the smoothness of a diamond’s facets. During the cutting and finishing process, microscopic marks or surface blemishes may form, which can influence the way light interacts with the stone. IGI grades polish on a five-point scale from Excellent to Poor.

Symmetry
Symmetry assesses how precisely a diamond's facets are aligned and proportioned. Even slight variations can impact how light travels through the stone, affecting its brilliance. IGI evaluates symmetry on the same five-point scale, ensuring that your diamond is cut for maximum sparkle.

Fluorescence
Fluorescence describes how a diamond reacts under UV light. While this typically has little effect on the diamond’s appearance in natural lighting, it can influence value. IGI includes fluorescence details in its reports to provide full disclosure on each diamond's characteristics.

This section may also include laser engravings, inscriptions, or additional gemologist comments regarding your specific stone.

Some are, IGI certifies and provides grading reports similar to those from other gemological institutes for both natural and lab-grown diamonds. However, IGI is particularly well known for its leadership in grading lab-grown diamonds, where it is considered the most trusted authorities in the industry.

For natural diamonds, GIA (Gemological Institute of America) is the gold standard, while IGI is widely preferred for lab-grown diamonds due to its deep expertise in that category.

Joshua James only sells GIA certified natural diamonds and IGI certified lab-grown diamonds.

Lab-grown diamonds are often considered a more eco-friendly alternative to natural mined diamonds, but the extent of their environmental impact depends on how they are produced. 

Any Lab-grown diamond is a more ethical and eco-conscious choice compared to like-for-like mined diamond, but not all lab diamonds are produced the same way; High Pressure High Temperature (HPHT)—can consume large amounts of energy, especially if fossil fuels are used, still much less compared to mining, but not as eco-friendly as CVD (Chemical Vapour Deposition) which is a more scientifically advanced method where diamonds are grown in a controlled chamber using carbon-rich gas and microwaves.

Your IGI Diamond certificate will state how the diamond has been grown in the comments section under the 'Additional Grading Information'.

Less Land Disruption – Unlike mined diamonds, lab-grown diamonds do not require large-scale excavation or deforestation.
Lower Carbon Footprint – Traditional diamond mining involves heavy machinery and transportation, which emit significant greenhouse gases. In contrast, lab-grown diamonds can be produced with renewable energy, reducing emissions further.
Minimal Water Usage – Diamond mining consumes vast amounts of water, whereas lab-grown production generally requires much less.