The diamond buying guide

Mar 13, 2023

Diamond ring at The Perth Mint

Buying diamonds can be a confusing and overwhelming experience, especially if you are new to the process. Here is a guide to help you navigate the process of buying quality diamonds here in Australia.

Cut, clarity, colour, carat

When buying a diamond, it is important to understand the four Cs: cut, clarity, colour and carat weight. These are the primary factors that determine a diamond's value and quality.


The cut of a diamond refers to the angles and proportions that determine its ability to reflect light and create an optical effect known as fire or dispersion – essentially the sparkle. A well-cut diamond will have a bright and glittering appearance, while a poorly cut diamond will appear dull and lack lustre. Though it’s important to note that certain cuts of diamond, such as an emerald cut, will emit less brilliance due to its facets when compared to a round cut, though rough diamonds are emerald cut to showcase the almost perfect clarity of that diamond.


The Gemological Institute of America (GIA), one of the leading sources of knowledge, standards and education in gems based in the US, scale diamonds into the categories below. This is also the scale most used in Australia when determining diamond clarity:

  • Flawless (FL). No inclusions or blemishes visible under 10x magnification.
  • Internally flawless (IF). No inclusions visible under 10x magnification.
  • Very, very slightly included (VVS1 and VVS2). Inclusions so slight they are difficult for a skilled grader to see under 10x magnification.
  • Very slightly included (VS1 and VS2). Inclusions are observed with effort under 10x magnification but may be characterised as minor.
  • Slightly included (SI1 and SI2). Inclusions are noticeable under 10x magnification.
  • (I1, I2, and I3). Inclusions are obvious under 10x magnification which may affect transparency and brilliance.


The colour of a white diamond is judged based on its absence of colour. The whiter a diamond is, the higher its value (unless you’re specifically looking for coloured diamonds). Diamonds are rated on a scale from D (no colour – which is considered to be the most desired option) to Z (a noticeable yellow or brown tint – which is not so well desired). More specifically, D-E-F are in the colourless range; D being the best and more colourless than E, with E being more colourless than F.

Carat weight

Carat weight is a measure of a diamond's size and is the weight measurement used to determine a diamond's value. One carat is equal to 0.2 grams. Keep in mind that a higher carat weight does not always mean a better diamond. The quality of a diamond's cut, clarity, and colour are all key factors to be considered holistically.

It’s important to keep in mind that not all diamonds are created equal and a diamond with a higher rating in one of the four Cs may have a lower rating in another.

Choosing a reputable jeweller

When buying diamonds, it’s important to choose a reputable jeweller, one with a strong reputation in the industry. Check for reviews from previous customers to ensure that you are getting a high-quality diamond from a trusted and ethical source.

Ask for certification from reputable diamond certifiers such as the GIA, International Gemological Institute (IGI), Hoge Raad voor Diamant (HRD) or European Gemological Laboratory (EGL) as these certificates provide important information about the diamond's quality and origin and can help you make an informed buying decision.

Examine the diamond closely before making your purchase. Ask the jeweller to let you see the diamond under a microscope so you can inspect it for any flaws or inclusions.

By following these steps, you can be confident that you are making a well-informed decision when buying diamonds in Australia. With a little bit of research, you can find the perfect diamond to last you a lifetime.

The Perth Mint jewellery boutique

You can find The Perth Mint’s jewellery store inside our landmark heritage-listed building, established by Britain’s Royal Mint in 1899 at our iconic East Perth site in Hay Street.

Our elegant jewellery boutique is home to some of the world’s most exclusive diamond jewellery. Many of our hand-selected jewellery pieces are accompanied by a certificate of authenticity, as well as the peace of mind that comes with choosing to make a purchase from a Government of Western Australia-owned enterprise with a long-standing reputation for quality and integrity.

Our experts will be happy to assist you to try on beautiful diamond jewellery of your choice. See how it looks against your skin, ensuring your masterpiece reflects your true individuality.

Come and explore today or book an appointment now.