Diamonds and coloured stones - everything you need to know
An honest guide to diamonds and coloured gemstones. Covering the 4 Cs, lab grown vs natural, shapes, popular gemstones, and ethical sourcing - written to help you choose with confidence.
Book a stone consultationWhat should I know before choosing a diamond or gemstone for my ring?
Whether you are choosing a diamond or a coloured gemstone, the key is understanding what drives quality and value in that specific stone. For diamonds, that means the 4 Cs - cut, colour, clarity, and carat - and the choice between natural and lab-grown. For coloured stones, it means understanding hardness, treatment, and origin. At Robbie Chapman Jewellery in Sydney, we guide every client through these decisions in a private consultation, bringing stone options for you to see and compare in person before committing to anything.
Lab grown or natural diamond?
This is the question we get asked most. Both are real diamonds. The difference is where they came from - and what that means for your budget and values.
Natural diamond
Formed over billions of yearsNatural diamonds are formed deep within the earth over billions of years. Each one is genuinely unique - no two are identical in their inclusions, growth patterns, or character.
They carry an inherent rarity that many clients find meaningful for an engagement ring. Natural diamonds also hold their value more reliably over time than lab-grown stones.
For a given budget, a natural diamond will typically be smaller or carry more inclusions than a lab-grown equivalent. Ethical sourcing is an important consideration - we source only from certified conflict-free suppliers.
Lab-grown diamond
Identical in every scientific senseLab-grown diamonds are produced in a controlled environment that replicates the conditions under which natural diamonds form. They are chemically, physically, and optically identical to mined diamonds.
The practical advantage is significant: a lab-grown diamond typically costs 60-80% less than a comparable natural stone. That means more carat weight, better cut, or better clarity for the same budget.
They have a lighter environmental footprint than mining, though the energy required to grow them is still substantial. Their resale value is currently lower than natural diamonds.
Robbie Chapman Jewellery offers both. Our position is simple: we present the honest facts about both options and let you decide what matters most to you. There is no right answer - only the right answer for you. We are happy to walk through both in detail at your consultation.
Cut, colour, clarity, carat
Every diamond is graded on four characteristics. Understanding how they interact - and which to prioritise for your specific ring and budget - is the key to choosing well.
| Factor | What it means | Robbie's guidance |
|---|---|---|
| Cut | How well the diamond has been shaped and faceted - not its outline shape, but the quality of the craftsmanship. Determines how light moves through the stone. Graded Excellent, Very Good, Good, Fair, and Poor. | Prioritise cut above all else. An Excellent-cut diamond in a lower colour or clarity grade will outshine a poorly cut stone of higher grades. |
| Colour | Graded D (colourless) to Z (noticeably yellow or brown). The less colour, the rarer and more valuable. Most engagement ring diamonds fall D to G. | I normally recommend my clients around 'E' to 'G' or better, as I find them to be the best value for money. 'G' is above average and nearly white. |
| Clarity | The presence of internal inclusions or surface blemishes. Graded Flawless to Included. Most inclusions are not invisible to the naked eye. | Eye-clean is the practical standard. VS2 or SI1 typically offers excellent value - inclusions invisible in normal wear. |
| Carat | The unit of weight. One carat equals 0.2 grams. Larger diamonds are exponentially rarer and more expensive per carat. | Buying just below round numbers (0.9ct vs 1.0ct) can save 15-20% with no visible size difference to the eye. |
Choosing a diamond shape
Shape is one of the most personal decisions in choosing a diamond. It determines the personality of the ring more than almost any other factor.
Round Brilliant
The classic. Maximises light return and brilliance. Most popular cut for engagement rings.
Oval
Elongates the finger and appears larger than a round of the same carat. Very popular and flattering.
Cushion
Soft rounded corners with a romantic, vintage character. Excellent light performance.
Emerald
Sophisticated step-cut rectangle with art deco character. Clarity is more visible in this cut.
Princess
Square brilliant cut with strong contemporary lines. Excellent brilliance, slightly lower price than round.
Pear
Teardrop shape - elegant and distinctive. Strongly elongates the finger.
Radiant
Rectangular brilliant combining emerald lines with round brilliance. Versatile and flattering.
Marquise
Pointed oval with dramatic presence. Maximises perceived size, strongly elongates the finger.
Beyond diamonds - coloured gemstones
Diamonds are not the only option for a centre stone. Coloured gemstones have a long history in fine jewellery and can make for a deeply personal and distinctive ring. The key consideration beyond beauty is hardness - a stone worn daily needs to be durable enough to withstand everyday life.
Sapphire
Hardness 9 on Mohs scaleThe hardest coloured gemstone after diamond and ideal for everyday wear. Available well beyond classic blue - pink, yellow, white, and padparadscha sapphires are all beautiful for engagement rings. Sri Lankan and Australian sapphires are particularly prized.
Ruby
Hardness 9 on Mohs scaleThe same mineral family as sapphire (corundum) and equally hard. Deep red rubies from Burma and Mozambique are among the most valuable coloured stones in the world. A ruby centre stone makes for an extraordinarily striking ring.
Emerald
Hardness 7.5-8 on Mohs scaleBeloved for its rich green colour. Softer than sapphire and ruby, so requires a protective setting for everyday wear. Almost all emeralds carry natural inclusions - these are considered part of the stone's character rather than flaws. Colombian emeralds are the benchmark for quality.
Morganite
Hardness 7.5-8 on Mohs scaleA blush pink member of the beryl family (same as emerald and aquamarine). Its soft peachy-pink tones pair beautifully with rose gold and have made it increasingly popular for engagement rings. Good durability for everyday wear.
Aquamarine
Hardness 7.5-8 on Mohs scaleA pale to medium blue beryl with exceptional clarity. Aquamarines are typically very clean stones - inclusions are rare. The cool blue tone pairs beautifully with white metals. Good hardness makes it suitable for engagement rings with appropriate care.
Alexandrite
Hardness 8.5 on Mohs scaleOne of the rarest and most remarkable gemstones - it changes colour from green in daylight to purple-red under incandescent light. Fine alexandrite is rarer and more valuable than many diamonds. A stone for those who want something truly extraordinary.
Where your stone comes from
We believe you have the right to know the origin of your stone. Every natural diamond we source is conflict-free and certified. Every lab-grown diamond comes from vetted suppliers. Here is what the key certifications mean.
GIA - Gemological Institute of America
The world standard in diamond grading. A GIA certificate provides independent assessment of cut, colour, clarity, and carat. We consider GIA certification the minimum standard for any diamond we supply.
IGI - International Gemological Institute
A widely trusted independent laboratory particularly common for lab-grown diamonds. IGI-certified lab-grown diamonds are graded to the same standard as natural diamonds.
Kimberley Process
An international certification scheme that prevents conflict diamonds from entering the market. All natural diamonds we source are Kimberley Process certified as conflict-free.
What people ask us about diamonds and gemstones in Sydney
Yes. Lab-grown diamonds are chemically, physically, and optically identical to mined diamonds. They are graded by the same laboratories using the same criteria. A gemologist cannot tell them apart without specialist equipment. The only difference is their origin and at Robbie Chapman Jewellery we take the same care when selecting either a natural or lab grown diamond.
For durability in everyday wear, sapphire and ruby are the best choices - both rate 9 on the Mohs hardness scale, just below diamond. Sapphire in particular has a long tradition in engagement rings and is available in a wide range of colours. Emerald, morganite, and aquamarine are also beautiful options but require a more protective setting and slightly more care.
The Mohs scale rates mineral hardness from 1 (talc) to 10 (diamond). For a ring worn daily, a centre stone ideally rates 7.5 or above - below this, the stone can be scratched by everyday dust and grit. Diamond rates 10, sapphire and ruby rate 9, emerald and aquamarine rate 7.5 to 8. A softer stone can still be used in a ring with a protective bezel or cathedral setting.
For most people, the practical standard is eye-clean - meaning inclusions are not visible to the naked eye at normal viewing distance. This typically means VS2 or SI1 for round brilliants, and VS1 or VS2 for step cuts like emerald and Asscher where inclusions show more readily. Flawless grades carry a significant premium with no visible benefit in everyday wear.
Yes - and we strongly encourage it. Diamonds and gemstones look different in person than in photographs, and how a stone performs in natural light is something you need to see for yourself. At Robbie Chapman Jewellery, we bring a curated selection of stones to every consultation so you can compare options side by side in a relaxed, private setting in Sydney.
There is no rule. The advice about spending two or three months salary is a marketing invention from the 1940s. Spend what feels right for your relationship and your financial situation. We work across a genuine range of budgets and will always help you find the best stone for what you want to spend - not try to push you higher.
Ready to choose your stone?
We bring diamonds and gemstone options to every consultation so you can see and compare stones in person. The consultation is free and completely obligation-free.