Every diamond is graded on four qualities, first codified by the Gemological Institute of America in the 1950s and now standard in the trade. Master these four and you'll choose with confidence — at any budget, for any piece.

Carat: weight, not size

Carat is a weight measurement (1 carat = 0.2 grams), not a size measurement. Two diamonds of the same carat weight can look quite different depending on how they're cut and what shape they're cut into.

A working guide:

• 0.25–0.50 ct — delicate studs, pendants, daily wear
• 0.75–1.00 ct — classic solitaires, statement studs, hoops
• 1.50–3.00+ ct — tennis bracelets, signature engagement pieces

One thing worth knowing: a well-cut 1.00 ct round can look larger than a poorly-cut 1.20 ct, because more of the light that enters the stone returns to your eye. Cut, not carat, is usually where to spend.

Colour: less colour, more white

Diamond colour is graded from D (completely colourless) to Z (noticeable warmth). The standard we hold at Isaac Westman is H–I or better — colourless to the naked eye in most settings, with the value advantage of not paying for a grade only a gemologist can distinguish.

• D–F — colourless. Reserved for high-investment pieces where the colour grade matters as much as the stone.
• G–H — near-colourless. No visible tint to the naked eye. Premium grade.
• H–I — near-colourless. The Isaac Westman standard.
• J–K and below — faintly warm. Not used in the collection.

Clarity: what you can and can't see

Clarity ranges from FL (flawless) to I3 (inclusions visible to the naked eye). The Isaac Westman standard is VS2 or better. At that grade, inclusions exist but are not visible without magnification — which is the point.

• FL–IF — flawless. For investment collectors.
• VVS1–VVS2 — very, very slight inclusions. Eye-clean and beautiful, but the price premium is most felt at scale.
• VS1–VS2 — very slight inclusions. The Isaac Westman standard. Eye-clean in all settings.
• SI1 and below — inclusions may be visible. Not used in the collection.

Cut: the only C humans control

Cut is the most important of the four — and the most overlooked. Carat, colour, and clarity are decided in the rough. Cut is decided at the cutter's wheel. A well-cut diamond returns up to ninety-nine percent of the light that enters it. A poorly-cut diamond loses most of that light through the side or the back.

The three qualities cut produces:

• Brilliance — white light reflected back up toward the eye
• Fire — coloured flashes (the spectral dispersion through the stone)
• Scintillation — sparkle as the diamond moves

We carry only Excellent and Very Good cut grades. The difference at the lower end of the cut scale is substantial — a Good-cut diamond at the same carat and colour can look noticeably smaller and duller. Cut is where we don't compromise.

Working specs by piece type

What we typically recommend, drawn from forty years of seeing what holds up on the hand and what doesn't:

Engagement rings. 1.00–1.50 ct centre stone, H–I colour, VS2 clarity, Excellent cut. The platinum six-prong solitaire is the classic for this combination.

Stud earrings. 0.50–1.00 ct per ear, H–I colour, VS2 clarity. The four-prong setting holds the stone high; the bezel sits flatter against the lobe.

Tennis bracelets. 3.00–5.00 ctw, H–I colour, VS2 clarity. The four-prong setting is the classic; three-prong lets more light through and reads brighter.

Pendants. 0.30–1.00 ct, H–I colour, VS2 clarity. Bezel and prong both work — bezel reads more modern, prong more classic.

Care

Diamonds are the hardest substance on earth, but their settings are not. Wipe with a soft cloth after wear. Clean weekly with warm water, a drop of mild dish soap, and a soft brush. Avoid bleach, chlorine, and abrasives. Have the prongs checked once a year — we offer complimentary annual inspection as part of every piece.

Diamonds and pearls don't store well together — the diamond surface is harder than the pearl and will scratch it over time. Separate compartments.

Why ours feel different

We've been sourcing diamonds since the early 1980s — initially as the supplier to retailers whose names you'd recognize, now under our own. Forty years of buying through the same cutters means we know the exact stones coming through, and we say no to most of them. The collection is small for a reason.

Enchanting. Intriguing. Refined.

Explore the Diamond Collection