How We Select Your Perfect Diamond

20th Feb 2025

Sara Spence

At Kate & Kole, we hand-select only the finest lab-grown diamonds, representing less than 1% of what’s available. From a vast pool of 750,000 stones, we refine our selection based on the highest standards—D-F colour, IF-VS1 clarity, and a triple excellent cut. Each diamond is carefully assessed to ensure it is free from unwanted tones and features, with a preference for CVD-grown stones for their superior brilliance and ethical sourcing.
Our process is meticulous. For example, when searching for a 2ct oval—our most sought-after shape—only around 1,000 diamonds make the cut. We then take it further, prioritising stones with SCS-007 sustainability certification, reducing the selection to a rare few. Finally, our expert diamond buyer, Maggie, with over 40 years of experience, handpicks the perfect stone—one that embodies both beauty and integrity.
Beyond the 4 Cs, we consider sustainability, certification, and value to ensure your diamond is truly exceptional. By working directly with the world’s leading growers, we guarantee exquisite quality without compromise. A Kate & Kole diamond isn’t just rare—it’s one of a kind.

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How We Choose Your Diamond

The stones we choose make up the smallest percentage of the highest quality stones available.
To help you understand just how many decisions come into choosing your stone, I’d like to walk you through some numbers.
Combining a few of the biggest lab grown diamond merchants, we have access to a pool of around 750,000 certified stones. From here, we start to filter down this pool based on the strict parameters we have in place to ensure our stones are of the highest quality.
The first thing we do is choose stones that are either D, E or F in colour and IF, VVS1, VVS2 or VS1 in clarity. This removes around 71% of stones leaving us with around 215,000 options. We then select triple excellent graded stones (cut, polish and symmetry) and make sure stones are not brown, green or milky (have no BGM present), which removes over half of the available stones, leaving us with 90,000 stones.
We then look for stones which have been grown using the CVD method, our preferred growing method, cutting our pool by two thirds.
The next two steps drastically impact our pool of stones—your chosen size and shape. For this exercise I am going to select a 2ct oval, our most popular size and shape.
We now have just over 1,000 stones available to purchase.

The last two steps are possibly the most important steps, narrowing our pool to just 7 stones, before we pick your stone—the one.
We choose a stone which has been awarded the SCS-007* sustainability rating, a global independently assessed certifier ensuring our stones have been grown to the highest standards of sustainability and operate as carbon neutral growers. This step means we have just 7 stones to choose from as a team, or 0.00093% of the diamonds available to us.
The final hurdle is Maggie, our beautiful, talented diamond expert, who will let us know in a few words if the stone we have chosen is worthy. Maggie has been buying diamonds since 1979 and we are so lucky to have her.
Every diamond is unique, but a diamond chosen by our team is one-of-a-kind.
*SCS is the approved service provider to conduct RJC Code of Practices and Chain-of-Custody verification assessment. Interestingly when we looked into the sustainability rating, no HPHT stones were awarded this rating which further backs up our decision to choose CVD grown stones.

The Seven Cs™

Selecting your stone is the single most important step our team does for you during the process of getting your piece ready to be made. There are two key things that separate our stones from other options on the market. The credentials we use to choose your stones and the price we pay for our lab grown diamonds. The following article explains the parameter we use to ensure we choose the perfect stone. This is a combination of certification (The 4 C’s and the diamond certifier) and human experience (the combined experience of our bespoke team and our incredible diamond buying veteran, Maggie).
When choosing a diamond, it's important to understand the 4 Cs, which represent the key factors that determine a diamond's quality and value. Here's a breakdown of the 4 Cs, along with three additional Cs to consider when selecting a diamond:

1. Cut

The cut of a diamond refers to how well it has been shaped and faceted to reflect light. A well-cut diamond will exhibit more brilliance and sparkle, making it more desirable. The cut is often considered the most important of the 4 Cs, as even a high-quality diamond can appear dull if it's poorly cut. Diamond cuts are graded from Excellent to Poor.

2. Clarity

Clarity measures the presence of internal or external imperfections, known as inclusions or blemishes, in a diamond. A diamond with fewer imperfections will have a higher clarity grade and appear more flawless. Clarity is graded on a scale ranging from Flawless (no imperfections) to Included (visible imperfections).

3. Colour

Diamonds are graded based on their lack of color, with the highest quality diamonds being completely colorless. The color grading scale ranges from D (colorless) to Z (light yellow or brown). Colorless diamonds are more rare and valuable, but near-colorless diamonds (grades G-H) can offer excellent value while still appearing white to the naked eye.

4. Carat Weight

Carat weight refers to the size of the diamond. While larger diamonds are more rare and valuable, carat weight alone doesn’t determine a diamond’s beauty. The diamond's cut, clarity, and color should all be considered to find a stone that looks stunning at any size.

In addition to these traditional 4 Cs, here are three more important factors to consider:

5. Certification

A diamond’s certification ensures it has been graded and authenticated by an independent gemological laboratory. The Gemological Institute of America (GIA) is the most trusted and respected certification body, known for its stringent standards. A GIA (est 1931) certificate provides a detailed analysis of the diamond’s 4 Cs, giving you confidence in the accuracy of its quality. IGI certifies the largest quantity of stones on the market. Sometimes when we are unable to find a suitable GIA certified stone we select an IGI certified stone however we will look to upgrade your stone to allow for small inconsistencies with this newer (est 1975) certifier.
You may also want to seek out a Sustainability Certificate to ensure that the diamond has been sourced responsibly and meets environmental and ethical standards. Such certifications can confirm that the diamond is conflict-free and that its production process adheres to sustainable practices.
To explain this further, when choosing a stone we sometimes find that when we put all our desired parameters into our stone selection process, the results are 0. We then have to make a decision for our client which is the most important element to their stone selection. If sustainability is the most important factor, we may open our search up to both GIA and IGI certified stones to find one with a SCS certificate. Or, if they’re after a particular ratio we may need to widen our search even further. The best outcome for our customers is to be as strict with our parameters while being consciously flexible to achieve the look they want.

6. CVD (Chemical Vapor Deposition) Diamonds

CVD is an advanced method of growing lab-grown diamonds, offering an alternative to the HPHT (High Pressure High Temperature) process. CVD diamonds are created in a controlled environment by layering carbon atoms to form a crystal structure, mimicking the natural process by which diamonds form. CVD diamonds tend to have fewer defects and inclusions, and they allow for more precise control over the diamond’s quality, making them a preferred choice for many buyers seeking lab-grown diamonds. CVD stones tend to be grown in regions where sustainability certification is prioritised. Of the 3,500 stones with a SCS-007 sustainability rating 96% were CVD grown, proving further the benefits of a CVD grown stone.
By considering these 6 Cs, you can make a more informed decision when selecting the perfect diamond, balancing both traditional factors and modern concerns like sustainability and advanced growing processes.

7. Cost

Depending on the size of the diamond we make between a 30-60% mark up on a stone, with larger mark ups on smaller stones and smaller margins on higher value stones. Sometimes our customers will look into the option of supplying their own stones, however with our direct access to trade suppliers and growers we are almost always able to secure a stone for a better price even including our mark up. When you build a ring in our jewellery builder or choose a design for our signature suite, a budget for your stone is set. We then purchase the diamond with that price point. This is a very important part, as making sure we spend the set budget on your stone is what sets us apart. If you go to purchase a diamond (whether it be mined or lab grown) you will notice a price disparity between two stones with the same grading. In an example we ran, a E VVS2 1ct round sone could vary in price by up to 80%. There are many things that impact this price outside of the 4 Cs. A higher priced stone is often grown in the USA, Singapore or Europe. Add in a SCS rated stone and there was a 150% increase. GIA graded stones on average were around twice the price of a different certifier in this category.
A grower that actively seeks out the GIA and SCS-007 rating is a grower that is looking to produce the best stones in the world. And these are the stones we are sourcing for you.
The overall price of lab grown diamonds has come down in recent years. But we have seen this impact stones of a lower quality to the stones we select. Lab Grown diamonds of the highest quality that are grown sustainably and certified correctly are beautiful and expensive and worth your consideration.

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