Loose Lab Grown Diamonds: How to Choose Before Buying

Decide how the diamond will be used and which features matter most to you. For a ring, consider the outline you prefer, the amount of finger coverage you want and the setting style. For a pendant, consider the diamond’s orientation and how it will sit within the design.

If you already own a mounting, involve the jeweller who will set the diamond before making a shortlist. Ask for the dimensions and other requirements the mounting can accommodate.

Set a budget for the complete project. Allow for the diamond, mounting, setting work and any additional charges that apply. This gives you a practical stone budget while keeping the finished jewellery within reach.

Carat measures weight. It does not tell you the diamond’s visible dimensions. GIA defines one metric carat as 200 milligrams and distinguishes weight from size in its carat-weight guidance.

For a round diamond, compare its recorded diameter measurements and depth. For an oval, pear, emerald cut or another elongated shape, compare length, width and depth in millimetres. These details help you understand the outline and give your jeweller information needed to assess setting fit.

For illustration, an oval measuring 8.40 × 5.60 mm has a length-to-width ratio of 1.50. An oval measuring 8.80 × 5.40 mm has a ratio of approximately 1.63. The second example is longer and narrower.

Use that ratio to compare outline preferences. Assess cut quality separately: a particular ratio does not establish how attractively the diamond handles light.

Request the grading document associated with the stone being offered. Check the laboratory, report or assessment number, laboratory-grown identification, shape and measurements. Review the quality information and comments included in that document.

IGI’s laboratory-grown diamond report information explains its grading approach and how growth-process or treatment information may be recorded. Read any comments supplied rather than assuming every report contains the same additional information.

Report formats also differ between laboratories. GIA’s current service for eligible colourless and near-colourless laboratory-grown diamonds provides a Premium or Standard quality assessment. Review the actual document and the criteria behind its assessment when comparing it with another laboratory’s report. GIA laboratory-grown diamond services.

Check the number through the issuing laboratory’s official verification service and compare the returned details with the seller’s information. Online verification checks the document record; the physical diamond must also correspond to it.

Our guides to IGI lab-grown diamond reports and GIA lab-grown diamond reports explain the documents in more detail.

Shape describes the diamond’s outline and cutting style. Cut quality concerns how its proportions and craftsmanship affect its appearance. When a listing includes a cut grade, establish who assigned it and check the accompanying report.

Excellent polish and symmetry describe particular aspects of finish. They should not be treated as a substitute for an overall cut assessment.

Fancy shapes can also receive cut grades. IGI’s published approach considers proportions, craftsmanship and light return alongside polish and symmetry. Its guidance explicitly recognises that proportions alone cannot establish fancy-shape cut quality. IGI cut-grading methodology.

For your shortlist, combine the documented assessment with a visual review. Look at how brightness and contrast change as each stone moves. If a central area appears persistently dark, request additional views or a gemmologist’s explanation before deciding whether its appearance suits you.

Colour grading takes place under controlled conditions. GIA explains that precise lighting and comparison with established masterstones are part of the process. An online photograph should therefore support your review rather than be used to assign a colour grade yourself. GIA diamond colour guidance.

Ask to compare shortlisted stones under similar lighting, and discuss any tint you notice with the seller. Consider the overall appearance you prefer and how the diamond will be used in your design.

For clarity, separate magnified detail from everyday visibility. GIA explains that many inclusions and blemishes are not visible without magnification and that clarity evaluation uses 10× magnification. GIA diamond clarity guidance.

If a seller describes a diamond as “eye-clean”, ask what viewing distance, lighting and orientation that description refers to. Review the particular stone rather than assuming a grade guarantees your preferred appearance.

Confirm that the images show the diamond you are considering. A representative photograph can illustrate a shape, but it cannot show the individual characteristics of another stone.

Request a face-up view, a side view and a rotating video where available. Compare shortlisted diamonds using similar lighting and magnification. If you can view them in person, look at them under more than one lighting condition.

GIA’s buying guidance recommends reviewing diamonds in different lighting and using rotating views when shopping online. It also notes that similar grading information does not make two diamonds visually identical. GIA diamond-buying guidance.

Send the diamond’s measurements, report and available images to the jeweller who will complete the piece. Ask whether the stone suits the proposed mounting and whether any alterations or a different setting will be needed.

A mounting described for a particular carat size still needs to be checked against the actual diamond. Shape, length, width, depth and the stone’s profile can affect the work required.

If you are buying the diamond from one business and having it set by another, confirm that the setter accepts customer-supplied stones. Agree the setting charge, anticipated work, timescale and how the diamond will be checked when received.

For a new custom design, ask when the mounting specifications will be finalised around the selected stone. Keep the diamond reference and approved measurements with the design information.

Ask for a written quotation identifying the exact diamond through its stock reference and report or assessment number. Confirm the currency, quotation validity and whether the stone is available or subject to confirmation.

Establish what the quoted amount includes. Shipping, insurance, applicable taxes, additional documentation and setting work should be clearly accounted for where relevant. Our lab-grown diamond prices guide explains the broader pricing considerations.

Before paying, understand the inspection and return arrangements. Ask when any inspection period begins, how a return is requested, which costs apply and whether setting or altering the diamond affects eligibility.

Arrange any independent inspection within the agreed period and before mounting begins. Keep the quotation, invoice, report and correspondence together.

Use this short comparison when deciding between your final options.

Where information is missing, ask for it before choosing. A useful shortlist makes the differences between stones understandable, so you can decide which combination of appearance, dimensions and cost suits your project.

To discuss a loose diamond with Uniglo Diamonds, share your preferred shape, approximate carat range, budget and intended jewellery design. Include any required measurements, reporting preferences or setting constraints.

If you have already selected a diamond from our inventory, include its reference in your enquiry. You can contact Uniglo Diamonds to ask about the specific stone, available documentation, current quotation and applicable terms.

For production quantities, parcels or recurring trade requirements, visit our wholesale lab-grown diamonds page.