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The stone guide
Understanding Your Stone
The diamonds and moissanite we work with are real, certified, and grown with renewable energy. This guide helps you understand what makes each stone exceptional — and how to choose what is right for you.
Where to start
The Four Things That Define a Diamond
Every lab-grown diamond is graded against the same four criteria as a mined diamond — color, cut, clarity, and carat. Understanding these lets you make a smart choice rather than just buying the biggest number. At Signora, every diamond comes with an IGI certificate confirming all four grades.
Color
How white or tinted
Cut
How it handles light
Clarity
Inclusions and flaws
Carat
Weight, not size
The 4Cs · Color
Color — The Less, The Rarer
Diamonds are graded on a D–Z scale, where D is completely colorless and Z shows visible yellow or brown tint. The absence of color is rarer and commands a higher price — but beyond H, the difference is almost invisible to the naked eye.
D–F
Colorless
G–H
Near colorless
I–J
Near colorless
K–Z
Faint to light
G–H
RecommendedVirtually white in most settings
Signora note
Best value — our recommendation
Signora tip
For most settings, G–H color gives you the look of a D at a fraction of the price. In yellow or rose gold, I–J can look completely white — the warm metal masks any tint.
The 4Cs · Cut
Cut — The Most Important C
Cut is not the shape of the diamond — it is how well the facets are proportioned, polished, and aligned to reflect light. A poorly cut diamond looks dull no matter how large or clear it is. A well-cut diamond of modest size will outshine a large, poorly cut one every time.
Poor
Fair
Good
Very Good
Excellent
Most experts agree: never compromise on cut. It is the single biggest driver of sparkle and brilliance.
Anatomy of the cut
Table — the large flat facet on top
Crown — the angled section above the girdle
Girdle — the widest edge, where the stone is held
Pavilion — the lower cone that returns light
Culet — the tiny point at the very bottom
Proportions affect how light enters, reflects, and exits the stone.
Signora tip
We select Excellent and Very Good cut grades across our collection. A round brilliant in Excellent cut is the benchmark of sparkle — any other shape should also prioritize cut quality.
The 4Cs · Clarity
Clarity — Imperfections That Are Mostly Invisible
Clarity measures inclusions (internal characteristics) and blemishes (surface marks) in a diamond. Almost all diamonds have them — the question is whether they are visible to the naked eye and whether they affect the stone's beauty or structural integrity.
◇
FL / IF
VVS1–VVS2
VS1–VS2
Sweet spot
SI1–SI2
I1–I3
Very Slightly Included VS1–VS2
Minor inclusions, not visible to the naked eye.
Signora tip
VS1–VS2 is the sweet spot — eye-clean stones at a significantly lower price than VVS or Flawless. We recommend VS2 or better for most pieces. SI1 can be eye-clean and represents excellent value — ask us to check before you buy.
The 4Cs · Carat
Carat — Weight, Not Size
Carat refers to the weight of a diamond, not its physical dimensions. A well-cut 1.9ct diamond can look as large as a 2.0ct — so buying just below a round number (1.9ct instead of 2.0ct, 0.9ct instead of 1.0ct) is one of the smartest ways to save without any visible difference.
The physical size also depends on the shape — a 1ct oval appears larger face-up than a 1ct round, because ovals have a larger surface area for the same weight.
0.5ct
≈ 5.2mm
1.0ct
≈ 6.5mm
1.5ct
≈ 7.4mm
2.0ct
≈ 8.2mm
2.5ct
≈ 8.8mm
3.0ct
≈ 9.4mm
4.0ct
≈ 10.2mm
Approximate face-up diameter for a round brilliant. Tap a stone to compare.
Signora tip
Our rings are available from 1.0ct to 4.5ct. For an engagement ring, 1.5ct–2.0ct is the most popular range — substantial without being overstated.
Shape
Shape — The Look That Defines the Ring
Shape is the physical outline of the stone as seen from above. It is often (incorrectly) called cut — but shape and cut are different things. Shape is a style choice; cut is a quality grade. Each shape has its own character.
Round Brilliant
The most brilliant shape. Maximizes sparkle. The classic choice.
Oval
Elongates the finger. Larger face-up appearance per carat. Romantic and modern.
Princess Cut
Bold square outline. Strong geometry, excellent brilliance. Contemporary.
Cushion
Soft rounded corners. Vintage warmth with modern appeal.
Pear
Unique teardrop silhouette. Slimming on the finger. Elegant and distinctive.
Emerald
Step-cut facets. Sophisticated hall-of-mirrors effect. Understated luxury.
Radiant
Brilliant-cut in a rectangular shape. Maximum sparkle in a longer outline.
Marquise
The most elongating shape. Dramatic and vintage-inspired.
Asscher
Square step-cut. Deep, geometric, architectural. A statement piece.
Heart
The most romantic shape. Best in 1ct+ for the outline to read clearly.
Signora tip
If you want the stone to look as large as possible for your budget, choose oval, pear, or marquise — their elongated outlines appear bigger than a round of the same carat weight.
Lab diamond vs moissanite
Which Stone Is Right for You?
We offer both IGI-certified lab-grown diamonds and GRA-certified moissanite. Both are real, beautiful, and ethical. Here is how they compare.
Both
Lab Diamond
Moissanite
IGI certified
Lab-Grown Diamond
GRA certified
Moissanite
Composition
Pure carbon
Silicon carbide
Hardness (Mohs)
10 — the hardest known material
9.25 — excellent durability
Brilliance
High (refractive index 2.42)
Very high (refractive index 2.65)
Light dispersion
White sparkle
Colorful "fire" — rainbow flashes
Certification
IGI certificate
GRA certificate
Price
Higher
Lower — more accessible
Ethical / origin
Grown with 100% renewable energy
Lab-created
Best for
Those who want a diamond, full stop
Those who want brilliance at better value
Moissanite's higher refractive index means it throws more colorful light ("fire") than a diamond. In sunlight this is spectacular. In candlelight both look equally stunning. The choice comes down to what matters to you — the name, the look, or the budget.
Signora tip
If you are unsure, book a consultation with Himmat. He can show you both side by side and help you choose based on your preference, occasion, and budget.
Pairing stones with metals
Which Metal Suits Your Stone?
The metal you choose affects how the stone looks as much as the stone itself. Here is a quick guide.
Signora tip
Rose gold is one of the most flattering metals for all stone types — it adds warmth and femininity without competing with the stone. Platinum is the most secure and durable long-term setting.
Still deciding?
Talk to the Person Who Makes Your Ring
Book a free 20–30 minute consultation with Himmat, Signora's founder and designer. No obligation — just honest advice about what will look best for your preferences and budget.