How Big is a Millimeter and other FAQ

Millimeter Conversion

1/4 Inch = 6.35 mm

US Dime = 17.80 mm

1/2 Inch = 12.70 mm

US Penny = 19.00 mm

1 Inch = 25.40 mm

US Nickle = 21.20 mm

Millimeter Converter

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Birthstone List












Alexandrite or Pearl








Opal or Tourmaline


Topaz or Topaz Quartz


Blue Zircon, Turquois, Tanzanite, or Lapis Lazuli

Wedding Anniversary Gifts


Traditional Gift

Modern Gift





















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 Gold Jewelry































Why Does Gold Discolor Fingers?

Your may think that faulty manufacturing or underkarating might be the problem when a ring "turns," blackening or discoloring the skin and clothing, or the jewelry itself. However, that is not the case.

The most common reason is metallic abrasion, caused by makeup on skin or clothing. Cosmetics often contain compounds harder than the jewelry itself, which wear or rub off very tiny particles. Very finely divided metal always appears black rather than metallic, so it looks like a jet-black dust. When this dust comes into contact with absorbent surfaces such as skin or clothing, it sticks, forming a black smudge.

To prevent this, you should try switching cosmetics. If this is not possible, we recommend that you remove rings and other jewelry while applying them, and clean skin areas in contact with jewelry with soap and water.

Another cause is actual corrosion of the metals. Gold itself does not corrode, but its primary alloys of silver or copper will do so—forming very dark chemical compounds—under moist or wet conditions. When you perspire, fats and fatty acids released can cause corrosion of 14-karat gold, especially when exposed to warmth and air.

This problem can be worse in seacoast and semitropical areas, where chlorides combine with perspiration to form a corrosive element that discolors skin. Smog fumes gradually attack jewelry and are evident as a tarnish that rubs off on the skin.

On several occasions I have come across the suggestion that a general iron deficiency or anemia can be the cause of this "black smudging". I am aware of no studies done to date on this correlation. Specifically, the correlation between a persons iron levels and their ph levels. I suggest that there is a direct and identical correlation between a persons iron level and their ph level. That is to say as their iron level decreases so does their ph levels. Their body chemistry becomes more acidic. Therefore, the cause of the discoloration would be the increase of acidity, as outlined above, and not the iron deficiency itself.

We suggest that you remove jewelry often and use an absorbent powder, free of abrasives, on skin that comes into contact with jewelry. Even the design of jewelry can be an influence. Wide shanks have more surface area to contact abrasives or corrosives. Concave surfaces inside a shank form collection points that trap moisture and contaminants, also causing a type of dermatitis.

You should remove all rings before using soaps, cleaning compounds or detergents, and clean your jewelry frequently. As well as solving the problem, you’ll be amazed at how much better your jewelry looks! As always, have your jewelry professionally inspected 3-4 times a year. A minor repair can become a major replacement if left unchecked.

Millimeter converter is courtesy of