Lab Grown Diamonds HPHT: What Buyers Should Know

Lab grown diamonds hpht are created by simulating the high pressure and high temperature required to produce a diamond crystal in a controlled manufacturing environment. This creates a genuine diamond material as opposed to an imitation (cubic zirconium or moissanite). It is worth being aware of HPHT for Australian diamond buyers, as the growth method can be mentioned in grading reports or stated by retailers. However, the choice of growth method does not indicate if a particular stone will be appealing, cut well or be suitable for your engagement ring. The individual diamond should be assessed to understand its appeal and value.

What Does HPHT Mean in Lab-Grown Diamonds?

HPHT stands for High Pressure High Temperature. Specialised equipment exposes a small seed diamond to conditions which promote diamond crystal growth and carbon material accumulates around the seed to form a larger diamond crystal that can be cut and polished. Natural diamonds also form in high pressure and high temperature conditions, although through a different mechanism underground. The key difference is that an HPHT-grown stone is laboratory-grown but has the same material qualities as a mined diamond. This is why laboratory-grown diamonds should not be confused with diamond simulants.

HPHT vs CVD: What Is the Difference?

HPHT and Chemical Vapour Deposition (CVD) are the main methods of producing laboratory-grown diamonds. CVD typically produces diamonds from carbon-bearing gases inside a chamber, with carbon atoms layering up on a diamond seed to gradually build a diamond crystal. HPHT grows a diamond using very high pressure and very high temperature, rather than depositing carbon atoms onto a seed. Neither growth method is inherently better than the other. A well-cut HPHT diamond can be far more attractive than a poorly cut CVD diamond and vice versa. The best approach is to treat the growth process as a reference point rather than focusing on it as the main quality indicator. Factor HPHT CVD Growth environment High pressure and high temperature Carbon bearing gases in a controlled chamber Final material Laboratory-grown diamond Laboratory-grown diamond Quality range Varies by individual stone Varies by individual stone Main buying focus Cut, colour, clarity, carat and grading Cut, colour, clarity, carat and grading

How Are HPHT Diamonds Graded?

Lab-grown diamonds can be measured using the standard 4Cs framework of cut, colour, clarity and carat. These factors describe different qualities of the stone.

Cut

Cut describes how well the proportions and craftsmanship of a faceted diamond work together to return light and create sparkle.

Colour

Colour relates to the amount or absence of body colour of lab diamonds according to the grading system utilised.

Clarity

Clarity considers the internal inclusions and external blemishes.

Carat Weight

Carat weight measures the lab made diamonds of the stone and two one-carat diamonds can have very different shapes and sizes due to differences in shape, depth and proportions. A grading report from a recognised laboratory may also include factors such as measurements, polish, symmetry, fluorescence and identifying characteristics. Australian diamond buyers looking at lab diamonds at retailers such as novitadiamonds.com can utilise these factors to compare individual stones rather than relying solely on the carat weight and growth method.

Why Cut Quality Deserves Extra Attention

For many faceted diamonds, the cut quality has a significant impact on the appearance of the diamond. A diamond with excellent light return can appear much brighter and have more sparkle compared to a diamond with lower quality proportions that appear dark and dull, despite having high grades for colour or clarity. This is particularly important for round brilliant diamonds where the cut is relatively straightforward to compare, whereas fancy shaped diamonds (oval, cushion, radiant, pear, emerald cuts) tend to need a more detailed assessment as the appearance can vary substantially despite a similar shape. Wherever possible, buyers should look beyond the headline cut grade and consider the dimensions, proportions, symmetry and how the face-up diamond appears in person to understand the differences between two diamonds that may appear similar on paper.

Does HPHT Affect Colour or Clarity?

The growing environment for an HPHT diamond can influence characteristics inside the diamond but it is not advisable to assume that all HPHT diamonds will have the same appearance. Individual lab-created diamonds can vary significantly in terms of their colour grade, clarity grade and internal characteristics. Some characteristics can only be seen using the correct laboratory equipment and are not apparent to the naked eye. What matters to the buyer is how the finished diamond has been graded and its actual appearance. Very high clarity grades are not necessarily required for an attractive diamond; if the inclusions are challenging to see without magnification and do not detract from the overall appearance, moving up the clarity scale may provide little additional benefit. The same principles apply to colour. The aim is often to balance the appearance, setting material, diamond shape and budget rather than strive for the highest possible grade.

Check the Grading Report Before Buying

A diamond grading report provides independent information about a laboratory-grown diamond. Depending on the laboratory and report format, this may include: carat weight, measurements details of colour and clarity grades information about the cut if applicable polish and symmetry fluorescence lab grown origin identifying characteristics report number Recognised grading organisations such as IGI and GIA evaluate laboratory-grown diamonds (although the report format and terminology may vary). A grading report should not be used as a financial valuation or guarantee about resale value; it describes the characteristics of the stone according to the laboratory’s grading methodology. Where a laser inscription is utilised, the report number may also be inscribed on the girdle of the diamond and can be used to assist with identifying the diamond.

HPHT Diamonds for Engagement Rings

HPHT-grown diamonds can be utilised in the same jewellery categories as other diamonds, including engagement rings, earrings, pendants and wedding jewellery. For an engagement ring, the growth method typically takes second place to the complete combination of stone and setting.

Consider

diamond shape and face-up size quality of cut and potential light performance stone colour and clarity ring profile and band width choice of metal such as platinum or white, yellow or rose gold stone protection resizing options wedding-band compatibility A solitaire style keeps the focus on the centre stone, whereas halo and pavé settings add more stones and provide a different appearance, with bezel settings offering more coverage around the centre stone but once again providing a different style. No single setting is perfect for every wearer.