How to Choose a Diamond: The Complete Guide
Choosing a diamond is an exciting and meaningful decision, often one of the most significant purchases in a lifetime. Whether you’re searching for an engagement ring, a timeless gift, or a personal investment, understanding what makes a diamond truly exceptional is essential. In this guide, we break down how to choose a diamond with confidence, using the internationally recognised 4Cs: Cut, Colour, Clarity, and Carat Weight.
1. Cut: The Most Important C
Of all the diamond characteristics, cut has the greatest impact on a diamond’s brilliance and sparkle. A well-cut diamond will reflect light beautifully, creating that signature fire and brilliance.
Excellent/Ideal Cut diamonds offer maximum sparkle.
Poorly cut diamonds, even if they’re large or clear, can appear dull.
At Polished Diamonds, all diamonds are cut to precise proportions using advanced 3D CAD technology to maximise light performance and beauty.
2. Colour: The Whiter, the Rarer
Diamonds are graded on a colour scale from D (colourless) to Z (light yellow or brown). The less colour a diamond has, the rarer and more valuable it is.
D–F: Colourless (premium quality)
G–H: Near-colourless (excellent value)
I–J: Slight warmth visible to the untrained eye
We recommend G–H colour diamonds for a great balance between beauty and budget.
3. Clarity: Natural Inclusions
Clarity measures how free a diamond is from internal inclusions or external blemishes. Most diamonds have tiny imperfections, but many are invisible without magnification.
FL to VVS: Flawless to Very Very Slight Inclusions (very rare)
VS to SI: Very Slight to Slight Inclusions (best value)
I1 and below: Eye-visible inclusions (less recommended)
For engagement rings, clarity grades of VS2–SI1 often offer the best mix of quality and affordability.
4. Carat Weight: Size and Presence
Carat refers to the diamond’s weight—not size. While a higher carat diamond looks larger, two diamonds of the same weight can appear different depending on their cut.
0.50–0.90ct: Great value with everyday wearability
1.00ct and above: Popular for engagement rings
1.50ct+ and 2.00ct+: Ideal for statement pieces or luxury clients
You can customise the diamond size based on your budget and the ring’s design.
5. Natural vs. Lab-Grown Diamonds
Lab-grown diamonds have grown in popularity for their ethical sourcing and affordable pricing. They are real diamonds—physically and visually identical to natural stones—but cost 30–50% less.
At Polished Diamonds, we offer both certified natural and lab-grown diamonds, allowing you to choose based on your preferences, values, and budget.
6. Certification Matters
Always choose a certified diamond from an independent grading lab such as GIA, IGI, or HRD. This guarantees the quality and authenticity of your stone.
Every diamond from Polished Diamonds comes with a trusted certificate, offering peace of mind and transparency.
7. Personalised Advice and Custom Design
Buying a diamond shouldn’t be overwhelming. At Polished Diamonds, we simplify the process with:
Expert guidance and free consultations
3D CAD design to visualise your custom ring
Matching wedding rings crafted to fit perfectly
We scan your engagement ring to create a wedding band that aligns perfectly, ensuring comfort and harmony.
Final Thoughts: Choose Quality with Confidence
When you know what to look for, choosing a diamond becomes a rewarding experience. Focus on the 4Cs, trust certified diamonds, and work with experts who understand your vision.
Visit the Polished Diamonds shops in Auckland, Wellington, or Christchurch, or browse our online collection to explore our award-winning designs and create a ring that tells your story. We provide personal assistance from our GIA-qualified staff, so simply contact our team – we like to help.
