Diamond Guide
How to choose a diamond
Learn the 4Cs and find a sparkle all your own
Choosing a diamond may seem difficult. But once you know the basics, it becomes a pleasure. We explain the four Cs, and something even more important, in a way that is easy to understand.
Cut comes first.It is the most important element in determining sparkle. For colour, an F grade or higher is safe, VS2 is plenty for clarity, and carat comes last, within your budget. If you are unsure, feel free to consult us at our Daikanyama store.
What are a diamond's 4Cs?
A diamond's quality is assessed by an international standard, the「4C」. The 4Cs are the initials of Carat (weight), Color, Clarity and Cut (polish).
This standard was established by the GIA (Gemological Institute of America) and is used throughout the jewellery industry worldwide. The balance of the 4Cs determines how a diamond looks and what it costs.
Carat
The carat (ct) is the unit for a diamond'sweight.One carat is 0.200 grams. It is often confused with size, but strictly it is a unit of weight. That said, for the same cut, a higher carat also means a larger size.
At ANNA DIAMOND we offer a wide range, from 0.3ct to over 2ct. Because these are lab-grown diamonds, you can choosea carat a step higher for the same budget.you can choose.
| Carat | Diameter (round) | A guide to use |
|---|---|---|
| 0.1ct | about 3.0mm | Melee diamonds, as accents |
| 0.3ct | about 4.3mm | An elegant size, suited to everyday wear |
| 0.5ct | about 5.2mm | A balance of presence and refinement |
| 1.0ct | about 6.5mm | A splendid presence |
| 2.0ct | about 8.2mm | For special jewellery |
| 3.0ct〜 | about 9.3mm and up | Please consult us |
Bigger is not always better. Even with a high carat, if the cut is poor the sparkle suffers.Prioritising cut quality over caratresults in a diamond that actually looks more beautiful. Even at 0.3ct, an excellent cut gives an eye catching sparkle.
Color
A diamond's colour is graded with lettersfrom D (completely colourless) to Z (pale yellow).The closer to D, the rarer and more highly graded, but in practice around the F grade a diamond looks all but colourless to the naked eye.
At ANNA DIAMOND we select on a basis ofF grade or higher.Diamonds with colour beyond the Z grade (such as brown diamonds) can also be made as fancy colour pieces through a full order.
At ANNA DIAMOND we select on a basis ofF grade or higher (colourless)is our basis of selection. When paired with a yellow gold ring, even a G grade can look beautiful through the interplay with the gold. For fancy colours such as brown diamonds, please consult us for a full order.
Clarity
Clarity assesses the fewness ofinclusionswithin a diamond and blemishes on its surface.10x loupe (a gemmological triplet loupe)It is judged by observing under a.
FL and IF are extremely rare and costly, butup to VS2 it is all but impossible to find inclusions with the naked eye.Considering budget, VS1 to VS2 can be called the grades with the best value. Rather than fixating on the numbers in the report, value whether it looks beautiful to your own eye.
Cut
Among the 4Cs, theone element decided by human handsis cut. The angles and proportions to which the rough is polished change how light reflects and refracts, and determine the sparkle.
The cut grade measures the efficiency with which light enters, reflects inside the diamond, and is released again from the top surface (the table and crown).Brilliance (white light), fire (rainbow light) and scintillation (sparkle)are the three elements assessed together.
A cut grade is officially assigned only to the round brilliant cut, and is graded on five levels.
At ANNA DIAMOND we select on a basis ofExcellent〜Very Goodwe use only the cut grade of. Cut is the element among the 4Cs most directly tied to visible beauty. Even when budget is limited, we recommendnever compromising on cut alone.That is our recommendation.
The order of priority in the 4Cs
This is only our opinion, but rather than seeking the highest grade in every C, we recommend choosing with good balance. To help you choose the most beautiful diamond within your budget, we introduce anorder of priority.
1st, cut: The most important element in determining sparkle. This is the one place we recommend not compromising.
2nd, colour: An F grade or higher is safe. Up to G, you will hardly ever sense a difference with the naked eye.
3rd, clarity: VS2 is plenty. Even SI1 can be fine depending on the position.
4th, carat: Decide this last, to suit your budget.
Diamond shapes
I always feel this myself when I design: simply changing the shape greatly changes the impression of the jewellery. Beyond round there are many shapes, each with its own character and way of sparkling.
At ANNA DIAMOND, centred on the round brilliant, we offer a variety of shapes such as oval, emerald and pear. For special shapes beyond these,a full order (Bespoke)can cut them from the rough. Feel free to consult us.
Lab-grown diamonds and natural diamonds
At ANNA DIAMOND we select on a basis oflab-grown diamonds.We share the difference from natural diamonds honestly.
A lab-grown diamond isa physically, chemically and optically identical materialto a natural one. In the Paris jewellery industry too, the handling of lab-grown diamonds has been steadily increasing in recent years.
At the same time, a natural diamond has a singular presence, nurtured by the earth over hundreds of millions of years. It is not that one is superior. We believe each has its own distinct appeal.
| Lab-grown | Natural | |
|---|---|---|
| Composition | Carbon (C) | Carbon (C) |
| Hardness | Mohs 10 | Mohs 10 |
| Sparkle | Identical | Identical |
| Grading | Assessed by the 4C standard | Assessed by the 4C standard |
| Environmental impact | Low | Requires mining |
| Price | 30 to 50% of natural | High |
| Asset value | Low | A degree of asset value |
A lab-grown diamond is materially identical to a natural one, butits asset value on the second hand market is low.That is the reality. For those who wish to leave it as an asset, a natural diamond is better suited. On the other hand, for those who wish to wear a larger, more beautiful diamond for the same budget, or to be mindful of the environment, lab-grown is a good choice. Rather than forcing this choice, we valueyour choosing it once you yourself are satisfied.That is what matters to us.
How diamonds are created and the supply chain
A lab-grown diamond is made by recreating the environment in which a natural diamond forms inside the earth. There are mainly two methods,the CVD method (chemical vapour deposition)and the HPHT method (high pressure high temperature).
At ANNA DIAMOND we create all of our diamonds by theCVD method.The CVD method deposits carbon atoms layer by layer from methane gas, yielding high quality crystals with few impurities.
The rough diamonds created are cut and polished by skilled artisans, pass IGI grading, and are crafted into jewellery at our own workshop in Japan. From the selection of the rough to the moment it reaches your hands,we ensure traceability at every stage.This is assured.
How to read a grading report
Thegrading report (grading report)that certifies a diamond's quality. At ANNA DIAMOND we take the report of the IGI (International Gemological Institute) as our standard.
Diamonds of 0.5ct and above come with an IGI grading report. For diamonds under 0.5ct too, a report can be obtained for those who wish (an additional fee applies).
The main items listed on a grading report
Report Number: A unique report number. You can verify its authenticity on the IGI site.
Shape & Cutting Style: The shape and cutting style.
Measurements: Dimensions (in mm).
Carat Weight: The carat weight.
Color Grade: The colour grade.
Clarity Grade: The clarity grade.
Cut Grade: The cut grade (round only).
Polish: The quality of polish.
Symmetry: Symmetry.
Fluorescence: Fluorescence.
Inscription: A unique number inscribed on the girdle (the side).
A lab-grown diamond's grading report clearly states「Laboratory Grown」. This does not mean the quality is inferior; it indicates transparency about how it was created.
ANNA DIAMOND's quality standards
From among the lab-grown diamonds of the world, we select each stone by our own standards.
Colour: F grade or higher (colourless)
Clarity: VS2 or higher
Cut：Excellent〜Very Good
Fluorescence：None〜Faint
Method: all created by the CVD method
Grading: 0.5ct and above come with an IGI grading report (available on request under 0.5ct too)
Frequently Asked Questions
There is a beauty that numbers alone cannot convey.ANNA DIAMOND
See it with your own eyes, and feel it with your heart.