Diamond Care Color Clarity Cut Carat weight Shapes Ring Size Table Millimeter mm to Inch in Converter Jewelry Stamping Hallmarks

The Four C's of a Diamond: Color, Clarity, Cut and Carat weight
Diamonds professionals use the following four factors to describe and classify diamonds: color, clarity, cut and carat weight. When taken together, they help in evaluating the finished diamonds you buy. That's why they are often called value factors.

Color

Diamonds in the normal color range are graded by their relative lack of color. A diamond that is said to have "fine color" has little or no visible coloration. The less color, the higher the value. Diamonds outside the normal color range are called fancy-colored and come in about any color you can imagine.
Fancy Colored Diamonds

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Clarity
Diamonds have internal features, called inclusions, and surface irregularities, called blemishes. Together, they’re called clarity characteristics. Clarity is the relative absence of clarity characteristics. Blemishes include scratches and nicks on a diamond’s surface. Inclusions are on the inside (some might break the surface of the stone, but they are still considered inclusions). Sometimes, tiny diamond or other mineral crystals are trapped inside a diamond when it forms. Depending on where they’re located, they might still be there after the stone has been cut and polished.
GIA Diamond Clarity Scale

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Cut
When looking for diamonds you may come across the terms, "Single Cut,” “Old Mine Cut” or “European Cut.” Single cut diamonds have a total of 17 facets. Most other designs have 58 facets.

Single cut diamonds are usually used on small accent stones and they won’t have the brilliance of a full cut diamond.

The cut of a diamond as a value factor, refers to its proportions, symmetry and finish. It is not to be confused with its shape.
Proportion refers to the angles and relative measurements of a polished diamond. More than any other feature, proportions determine a diamond's optical properties. Studies have shown that table size, crown angle, and pavilion depth have a dramatic effect on a diamond's appearance.
Diamond Proportions

Symmetry is a grading term for the exactness of shape and placement of facets. Variations in symmetry include off-center culets and tables, poor facet alignment, misshapen facets, out-of-round girdles, and wavy girdles.
Diamond Symmetry

The finish is the quality of a diamond’s polish, the condition of its girdle, and the precision of the cut.

Diamond Shapes
Shapes other than the standard round brilliant shown above are called fancy shapes or fancy cuts. Their names are based on their shapes. The best known are the heart, marquise, pear-shaped cut, emerald-cut, oval, and radiant.

Carat Weight
Diamonds are weighed to a thousandth (0.001) of a carat and then rounded to the nearest hundredth, or point. Over a carat, diamond weights are usually expressed in carats and decimals. A 1.03 ct. stone, for example, would be described as "one point oh three carats," or "one oh three." A diamond that weighs 0.83 ct. is said to weigh "eighty-three points," or an "eighty-three pointer." According to the 1907 international standard, one carat is equivalent to 0.2 gram.

The cumulative diamond weight of a piece of jewelry that includes several diamonds is measured in TCW (total carat weight) or pttw (points total weight) or Carats Total Weight (Carat TW). One TCW/Carat TW is equal to 100 pttw. For example, a diamond pendant with 83 pttw dia will have a total diamond weight of 0.83 carat or 0.83 TCW/Carat TW.
Popular Diamond Carat Weights

Some weights are considered "magic sizes" – half carat, three-quarter carat, carat. Visually, there’s little difference between a 0.99 ct. diamond and one that weighs a full carat. But the price differences between the two can be significant.

Many people would like to understand carat sizes in real terms. Here are some approximate, sample carat-weight to diameter-widths for Round* cut diamonds in popular sizes:
0.25 carat = 4.1 mm 0.50 carat = 5.2 mm
0.75 carat = 5.8 mm 1.00 carat = 6.5 mm
*Click here for Pear, Marquise, Oval, Emerald, Heart, Trillion & Princess mm to carats conversion chart or download and print PDF file (requires Adobe Acrobat Reader).

PS. Stone sizes are approximate. These charts are used for quick reference only. Stones should always be measured and/or weighed for accuracy.

Carats to Millimeters Conversion Chart for Round Diamonds
Carats	Diameter (mm)	Carats	Diameter (mm)
.005	1.0	1.25	7.0
.0067	1.15	1.33	7.2
.01	1.3	1.50	7.4
.015	1.5	1.60	7.6
.02	1.7	1.75	7.8
.025	1.8	1.90	8.0
.03	2.0	2.00	8.2
.035	2.1	2.15	8.4
.04	2.2	2.25	8.6
.05	2.4	2.50	8.8
.06	2.5	2.65	9.0
.07	2.7	2.85	9.2
.08	2.8	3.00	9.4
.09	2.9	3.15	9.6
.10	3.0	3.35	9.8
.11	3.1	3.50	10.0
.12	3.2	3.75	10.2
.14	3.3	4.00	10.4
.15	3.4	4.25	10.6
.16	3.5	4.50	10.8
.17	3.6	4.75	11.0
.18	3.7	5.00	11.2
.20	3.8	5.25	11.4
.22	3.9	5.50	11.6
.23	4.0	5.75	11.75
.25	4.1	5.81	11.8
.30	4.2	6.00	11.9
.33	4.4	6.25	12.1
.35	4.5	7.00	12.5
.38	4.6	7.50	12.85
.40	4.8	7.75	13.00
.43	4.9	8.00	13.1
.47	5.0	8.23	13.25
.50	5.2	8.50	13.4
.60	5.4	8.75	13.5
.63	5.5	9.00	13.65
.65	5.6	9.20	13.75
.75	5.8	9.75	14.0
.80	6.0	10.34	14.5
.85	6.2	12.00	15.0
.95	6.4	12.92	15.4
1.00	6.5	13.17	15.5
1.10	6.6	14.50	16.0
1.17	6.8
Source: Gemological Institute of America (GIA)

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Ring Size Table
To determine your ring size:
- Find a piece of string or strip of paper not wider than 3/4"
- Circle it around the base of the finger
- Mark the point where the two ends overlap and measure the length. This will be the "Inside circumference."
- Refer to the following table to determine your ring size
Click here for more information about Ring Size.

Conversion Chart for Ring Sizes
Inside diameter		Inside circumference		Sizes
(in)	(mm)	(in)	(mm)	United States & Canada	United Kingdom, Ireland & Australia	Japan & China	Switzerland


0.458	11.63	1.44	36.5	0
0.466	11.84	1.46	37.2	¼
0.474	12.04	1.49	37.8	½	A
0.482	12.24	1.51	38.5	¾	A½
0.49	12.45	1.54	39.1	1	B	1
0.498	12.65	1.56	39.7	1¼	B½
0.506	12.85	1.59	40.4	1½	C
0.514	13.06	1.61	41	1¾	C½
0.522	13.26	1.64	41.7	2	D	2	1.5
0.53	13.46	1.67	42.3	2¼	D½
0.538	13.67	1.69	42.9	2½	E	3	2.75
0.546	13.87	1.72	43.6	2¾	E½
0.554	14.07	1.74	44.2	3	F	4	4
0.562	14.27	1.77	44.8	3¼	F½	5	5.25
0.57	14.48	1.79	45.5	3½	G
0.578	14.68	1.82	46.1	3¾	G½	6	6.5
0.586	14.88	1.84	46.8	4	H	7
0.594	15.09	1.87	47.4	4¼	H½		7.75
0.602	15.29	1.89	48	4½	I	8
0.61	15.49	1.92	48.7	4¾	J		9
0.618	15.7	1.94	49.3	5	J½	9
0.626	15.9	1.97	50	5¼	K		10
0.634	16.1	1.99	50.6	5½	K½	10
0.642	16.31	2.02	51.2	5¾	L		11.75
0.65	16.51	2.04	51.9	6	L½	11	12.75
0.658	16.71	2.07	52.5	6¼	M	12
0.666	16.92	2.09	53.1	6½	M½	13	14
0.674	17.12	2.12	53.8	6¾	N
0.682	17.32	2.14	54.4	7	N½	14	15.25
0.69	17.53	2.17	55.1	7¼	O
0.698	17.73	2.19	55.7	7½	O½	15	16.5
0.706	17.93	2.22	56.3	7¾	P
0.714	18.14	2.24	57	8	P½	16	17.75
0.722	18.34	2.27	57.6	8¼	Q
0.73	18.54	2.29	58.3	8½	Q½	17
0.738	18.75	2.32	58.9	8¾	R		19
0.746	18.95	2.34	59.5	9	R½	18
0.754	19.15	2.37	60.2	9¼	S		20.25
0.762	19.35	2.39	60.8	9½	S½	19
0.77	19.56	2.42	61.4	9¾	T		21.5
0.778	19.76	2.44	62.1	10	T½	20
0.786	19.96	2.47	62.7	10¼	U	21
0.794	20.17	2.49	63.4	10½	U½	22	22.75
0.802	20.37	2.52	64	10¾	V
0.81	20.57	2.54	64.6	11	V½	23
0.818	20.78	2.57	65.3	11¼	W		25
0.826	20.98	2.59	65.9	11½	W½	24
0.834	21.18	2.62	66.6	11¾	X
0.842	21.39	2.65	67.2	12	X½	25	27.5
0.85	21.59	2.67	67.8	12¼	Y
0.858	21.79	2.7	68.5	12½	Z	26	28.75
0.866	22	2.72	69.1	12¾	Z½
0.874	22.2	2.75	69.7	13		27
0.882	22.4	2.77	70.4	13¼	Z1
0.89	22.61	2.8	71	13½
0.898	22.81	2.82	71.7	13¾	Z2
0.906	23.01	2.85	72.3	14	Z3
0.914	23.22	2.87	72.9	14¼
0.922	23.42	2.9	73.6	14½	Z4
0.93	23.62	2.92	74.2	14¾
0.938	23.83	2.95	74.8	15
0.946	24.03	2.97	75.5	15¼
0.954	24.23	3	76.1	15½
0.962	24.43	3.02	76.8	15¾
0.97	24.64	3.05	77.4	16

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Caring for Diamond Jewelry
Diamond is the hardest natural substance on Earth. It can cut any kind of rock or metal, but only another diamond can cut a diamond. In fact, a diamond must be heated to a temperature of 1292 degrees Fahrenheit before it will burn. However, the oil deposited from the mere touch of a human finger can cause dirt to collect and make this nearly indestructible gemstone quickly lose its sparkling appeal. The Gemological Institute of America (GIA) offers the following tips on diamond care:

Handle your diamond carefully. Because diamonds are natural magnets for grease, they’re not easy to keep clean. Handling a diamond with your fingers provides enough oils from your skin (the type of “grease” that most affects diamonds) to change the way your diamond looks.

Clean your diamond regularly. A simple plan to keep your diamond jewelry always looking beautiful is to soak the diamond in an ammonia-based household cleaner (such as window cleaner) overnight, once or twice weekly. In the morning, remove the diamond from the cleaner and brush it with a soft, clean toothbrush (one that has not previously been used in any way, and that you reserve exclusively for cleaning your diamond) to remove any leftover dirt. Take extra care to brush the back of the diamond as this will be the area that has collected the most oil and dirt.

Be aware that fragile settings and estate jewelry won’t take kindly to being scrubbed with a toothbrush, so use a soft touch. Then, just rinse the diamond with water and wipe with a soft, lint-free cloth.

Don’t use harmful solutions. Chlorine (as in household bleach) or abrasives (such as household cleansers or toothpaste) should never be used when cleaning diamonds, especially those set in jewelry. These erode some of the metals often used in diamond settings, and may loosen prongs, or even dissolve the metal completely.

Sometimes an ultrasonic cleaner is necessary to remove encrusted dirt on diamonds. By sending high frequency sound waves through a detergent solution, ultrasonic cleaners cause vibrating fluid to remove accumulated dirt and grime. However, they can also shake loose stones from their mounting, so this method shouldn’t be used on fragile settings (or estate jewelry), and is best undertaken by a professional jeweler.

Regular cleaning will keep your diamond jewelry in gleaming condition and ready to sparkle on that special occasion. See also Jewelry Care.

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Caring for Pearl Jewelry
Pearls are softer and more delicate than other gemstones or precious metals. They should be stored separately from other jewelry or they can be scratched, nicked, cracked or otherwise damaged. Once damaged, a pearl cannot be repaired. Soft pouches and their original boxing are the best ways to store them.

Cleaning pearls is also a very careful task. Perfume, hair spray, vinegar, ink, chlorine, natural body oils and perspiration are all detrimental to your pearls' luster and brilliance; some are damaging to the pearl itself. It's best to apply perfume, hair spray and cosmetics prior to putting on your jewelry. After each wearing, your pearls should be gently wiped down with a soft cloth. Wash from time to time with MILD, nonabrasive soap and a soft cloth and let them air dry before wearing again. NEVER put your pearls into an ultrasonic!

If pearls are worn often, restringing is an important part of the care and longevity of your pearls. Make sure to have them restrung by a qualified jeweler. See also Jewelry Care.

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Platinum versus White Gold

Metal Density Comparing inch for inch, platinum is a heavier and denser metal than white gold. One can easily tell by the weight difference of the platinum.
Color Platinum has a darker white color than white gold. Platinum looks rather grayish. Over long periods of time, platinum maintains its grayish white color whereas white gold may eventually tinge to a very light yellow as a result of being exposed to skin acids.
Durability Platinum scratches easier than white gold.
Sheen White gold maintains its sheen longer than platinum. After polishing, white gold will look shinier for a longer time than platinum.
Wearability White gold wears thin over long periods of time. For example, a ring shank may have to be eventually replaced after fifty years. On the other hand, the shank on a platinum ring will remain as thick as it was on the day it was purchased.
Price The price of platinum is 3 to 4 times higher than the price of white gold
Maintenance Over time, occasional maintenance on platinum involves visits to the jeweler for re-polishing. Maintenance for white gold, however, can include re-polishing, rhodium finish re-plating, and/or eventual replacement of shanks.

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Millimeter (mm) to Inch (in) Converter Chart

Millimeter to Inch Converter Chart 1 inch [in] is equivalent to 25.40 millimeters [mm]
mm	Approx. inch
1 mm	1/32 in
2 mm	1/16 in
3 mm	3/32 in
4 mm	1/8 in
5 mm	3/16 in
6 mm	Just under 1/4 in
7 mm	Just over 1/4 in
8 mm	5/16 in
9 mm	Just under 3/8 in
10 mm	Just over 3/8 in
11 mm	7/16 in
12 mm	Just under 1/2 in
13 mm	Just over 1/2 in
14 mm	9/16 in
15 mm	Just under 5/8 in
16 mm	5/8 in
17 mm	Just under 11/16 in
18 mm	Just under 3/4 in
19 mm	Just over 3/4 in
20 mm	Just under 13/16 in
21 mm	Just over 13/16 in
22 mm	Just under 7/8 in
23 mm	Just over 7/8 in
24 mm	15/16 in
25 mm	1 in

Visual millimeter (mm) to inch (in.) conversion compared to USA coins

cm to inch ruler

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Gauge to Inches to Millimeters Conversion Table

B & S Gauge	Inch (Decimal)	Millimeter (mm)	Inch (Fraction)	B & S Gauge	Inch (Decimal)	Millimeter (mm)	Inch (Fraction)
1	0.289	7.348	.	17	0.045	1.149	.
2	0.258	6.543	.	18	0.040	1.024	.
.	0.250	6.350	1/4	19	0.036	0.912	.
.	0.234	5.953	15/64	20	0.032	0.812	.
3	0.229	5.827	.	.	0.031	0.795	1/32
.	0.219	5.556	7/32	21	0.028	0.723	.
4	0.204	5.189	.	22	0.025	0.644	.
.	0.203	5.154	11/64	23	0.023	0.573	.
.	0.188	4.762	3/16	24	0.020	0.511	.
5	0.182	4.621	.	25	0.018	0.455	.
.	0.172	4.366	11/64	26	0.016	0.405	.
6	0.162	4.115	.	.	0.016	0.396	1/64
.	0.156	3.969	5/32	27	0.014	0.360	.
7	0.144	3.664	.	28	0.013	0.321	.
.	0.141	3.572	9/64	29	0.011	0.286	.
8	0.128	3.263	.	30	0.010	0.255	.
.	0.125	3.175	1/8	31	0.0089	0.226	.
9	0.114	2.906	.	32	0.0080	0.200	.
.	0.109	2.778	7/64	33	0.0071	0.180	.
10	0.102	2.588	.	34	0.0063	0.160	.
.	0.094	2.381	3/32	35	0.0056	0.142	.
11	0.091	2.304	.	36	0.0050	0.130	.
12	0.081	2.052	.	37	0.0045	0.114	.
.	0.078	1.984	5/64	38	0.0040	0.100	.
13	0.072	1.828	.	.	.	.	.
14	0.064	1.628	.	.	.	.	.
.	0.063	1.588	1/16	.	.	.	.
15	0.057	1.449	.	.	.	.	.
16	0.051	1.291	.	.	.	.	.
.	0.047	1.191	3/64	.	.	.	.

INCH TO MILLIMETER CONVERSION CHART FOR EARRING BACKS & POSTS
	Inches	Millimeters			Inches	Millimeters
	.025	0.65			.050	1.270
	.028	0.711			.057	1.448
	.030	0.762			.060	1.524
	.032	0.813			.061	1.549
	.034	0.864			.063	1.600
	.036	0.914			.072	1.829
	.040	1.016			.085	2.159
	.042	1.067			.110	2.794
	.045	1.143			.123	3.124

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Pennyweight (DWT) to Ounces to Grams Conversion Table

DWT	OUNCE	GRAM	DWT	OUNCE	GRAM
10	0.5	15.550	340	17	528.760
20	1	31.104	350	17.5	544.311
30	1.5	46.655	360	18	559.863
40	2	62.207	370	18.5	575.415
50	2.5	77.759	380	19	590.967
60	3	93.311	390	19.5	606.518
70	3.5	108.862	400	20	622.070
80	4	124.414	410	20.5	637.623
90	4.5	139.966	420	21	653.174
100	5	155.518	430	21.5	668.725
110	5.5	171.069	440	22	684.277
120	6	186.621	450	22.5	699.829
130	6.5	202.173	460	23	715.381
140	7	217.725	470	23.5	730.932
150	7.5	233.276	480	24	746.484
160	8	248.828	490	24.5	762.036
170	8.5	264.380	500	25	777.588
180	9	279.932	510	25.5	793.139
190	9.5	295.483	520	26	808.691
200	10	311.035	530	26.5	824.243
210	10.5	326.587	540	27	839.795
220	11	342.139	550	27.5	855.346
230	11.5	357.690	560	28	870.898
240	12	373.242	570	28.5	886.450
250	12.5	388.794	580	29	902.002
260	13	404.346	590	29.5	917.553
270	13.5	419.897	600	30	933.105
280	14	435.449	610	30.5	948.657
290	14.5	451.001	620	31	964.209
300	15	466.553	630	31.5	979.760
310	15.5	482.104	640	32	995.312
320	16	497.656	650	32.5	1010.864
330	16.5	513.208	660	33	1026.300

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Weight Comparison

To find the weight of an article in a metal different from that in which it is now made:
1. Find the present metal in the first vertical column.
2. Multiply the present weight by the factor in the same horizontal row under the new metal.
Example: A sterling silver ring weighs 8 grams, what will it weigh in 14kt.?
3. Along the horizontal row marked Stg in the first column under the heading 14 Kt we find 1.25 x 8 = 10 grams, weight in 14 Kt.

Weight Comparison Chart

	Pt.	F.G.	22kt	18kt	14kt	10kt	9kt	F.S.	Stg
Pt.	1.00	0.90	0.82	0.70	0.60	0.53	0.53	0.49	0.48
F.G.	1.11	1.00	0.91	0.78	0.67	0.59	0.58	0.54	0.54
22kt	1.22	1.10	1.00	0.86	0.73	0.65	0.65	0.60	0.59
18kt	1.42	1.28	1.16	1.00	0.85	0.76	0.75	0.69	0.68
14kt	1.66	1.50	1.36	1.17	1.00	0.89	0.88	0.81	0.80
10kt	1.88	1.69	1.54	1.32	1.13	1.00	0.99	0.92	0.90
9kt	1.90	1.71	1.56	1.34	1.14	1.01	1.00	0.93	0.92
F.S.	2.04	1.84	1.68	1.44	1.23	1.09	1.08	1.00	0.99
Stg	2.07	1.87	1.70	1.46	1.25	1.11	1.09	1.01	1.00

This chart is not precise for all alloys of precious metals, however it will always provide a good indication within a reasonable tolerance.

Source: kitco.com

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Jewelry Stamping: Hallmarks
By law, jewelry items have to be marked with a metal purity hallmark and a trademark of the manufacturer/artist. Jewelry weighing below 2 grams does not require marking. Usually, hallmarks are found on the back side of the jewelry or near the clasps. Often, the marks are very small in size and require the use of a magnifying glass in order to observe their detail.

When a composition of metals is used in jewelry, the mark would correspond to the lowest value metal used. For example, 925 mark will appear on an item composed of both 14K Gold and Sterling Silver, 14K mark will appear on an item containing both 14K and 24K Gold, etc. The description of the item may, of course, include all types of metals and composites used for crafting the item.

Below is a list of hallmarks commonly used for marking jewelry:
24 Karat Gold - 24K or 999
22 Karat Gold - 22K or 917
21 Karat Gold - 21K or 875
18 Karat Gold - 18K or 750
14 Karat Gold - 14K or 585
14 Karat Goldfilled - 14K GF or 14K/20
10 Karat Gold - 10K or 417
9 Karat Gold - 9K or 375
Sterling Silver - 925
Pure Silver - 999
Platinum - Plat or .95 Plat

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Common Gemstome Cuts

Cabochon - Dome shape polished gemstone. One side of the stone is flat and the other is in dome shape.	Round Amethyst cabochons
Rose Cut - The stone is cut in way that its bottom is flat and the top is faceted.	Round faceted Smoky Quartz gemstone
Emerald cut / Octagon cut - Square or rectangle shaped stones with truncated corners. Facets run in steps parallel to the gemstone circumference.	Left to right: Iolite, Emerald and Ruby, emerald-cut gemstones
Faceted - Gemstone cut in a way to include many facets. The multiple facets structure increases light reflection and gives the stone a bright and shining look.	Faceted oval Citrine gemstones Faceted Crystal and Blue Goldstone beads
Brilliant cut / Diamond cut - The most famous faceted cut used for round gemstones. The stone is cut with 58 facets in a special geometry for very high light reflection. The incident light enters the stone through the flat top surface, circulates within the stone and reflected back from the top surface. Commonly used for diamonds.	Brilliant cut Blue Topaz and Iolite gemstones
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