Jewelry, Gems, & Minerals/Metal


QUESTION: Hello I got this item in a box of things, I am wondering if this metal is silver or platinum ? and what is this item ?It have a K on back that's what I think it is. Thank you for your time.

ANSWER: While I cannot tell you anything about the K on the back, the metal is a different story. You can do a few simple tests.

Silver is very reactive with sulfur, forming black silver sulfide. Place a corner of your object into some egg yolk. If the object is predominantly silver, the sulfur in the egg yolk will cause the immersed corner of your object to turn black. The tarnish can be removed with some silver polish and "elbow grease". However, jewelry pieces are rarely cast from pure metal, but are alloys or mixtures of several metals. The silver in the object will still tarnish, even if silver and platinum would be mixed together.

An easy way to distinguish different metals is a simple but ingenious density test. You need to get yourself one of those hanging postal scales ( or fish scales) and a calculator. Tie your object to a string (thread). Attach string with object to hanging scale and weigh. Record this number, we will call this Wa or weight in air. If not in grams, convert your number to grams. Now submerse the object hanging from the scale completely in water. Make sure it is not touching the bottom or sides of your water container and no parts are sticking out of the water into the air. The weight should be less because of the buoyancy of the water. We will call this weight Ww or weight in water, which also needs to be recorded. Again, if not in grams, convert to grams. Density is then calculated by Wa/(Wa-Ww) which gives you the density in grams per cubic centimeter. For comparison, water has a density of 1.0 g/cm^3 and common rocks a density of about 2.8 g/cm^3.

Now pure silver would have a density of 10.49 g/cm^3 while pure platinum with a density of 21.45 g/cm^3 is extremely heavy and you would easily feel it when hefting even a small platinum object. It has a density similar to gold, just a little bit higher. In comparison, platinum as well as gold would be about twice as heavy as lead. As stated above, jewelry pieces are rarely pure metal, so taking a density value that lies within -20% of mentioned densities still viable options.

Iron has a density of 7.9 g/cm^3 and nickel a density of 8.9 g/cm^3. Jewelry made out of these common metals would have much lower density values and would also feel less dense when hefting.

Hope these answer and simple tests will help you decipher your mystery metal.

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QUESTION: I did the egg test and it did not turn black, all so I did the test about putting the item in hydrogen peroxide and it Bubble . This item weight is 22.1 gr. Thank you for your time

ANSWER: I estimate the size of your object from the picture of being roughly 3.5cm x 3.5cm x 0.5cm. This makes a total volume of 6.13cm^3. You say the weight is 22.1g, which would give my an estimated density of 22.1g/6.13cm^3 = 3.6g/cm^3. That means that the object does not even approach any precious metal out there. If there was a significant precious metal content in your object, your weight should be at least 100g. If you send me the exact measurements of your object, I could do a quick calculation and estimate what the metal alloy might be.

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QUESTION: It is 1 2/16 " tall and 1 2/16 wide and at the Middle and in the center 1" and opening is 1/2" . Hope this help you.

Thank you for the drawing and measurements. However, with the data you have provided the results are even worse. After calculation I am obtaining a specific gravity of around 2.6 g/cm^3 which would indicate that your specimen is some type of an aluminum alloy. Other then the esthetic value I am afraid it is not worth much.  

Jewelry, Gems, & Minerals

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Uwe Richard Kackstaetter, Ph.D. (Dr.K)


I can answer questions concerning minerals, mineralogy, gems, metals, and anything that has to do with geology. However, I am NOT a jeweler. Questions about values, settings, gem stone cuts and appraisals are best directed to other experts on this site. I can however aide in the identification of unknown mineral materials. As a public service and part as training for new geoscientists, our university department provides FREE mineral identification for individuals. Please contact me for details or go to for details..


I am a professor of applied geology and mineralogy with many hours of field experience. Furthermore, I enjoy recreational gold prospecting and mineral collecting. As a professor I am engaged in research concerning minerals and their occurrence.

Member of the GPAA (Gold Prospectors Association of America) as well as the Association of Environmental Geochemists. Member of the GSA (Geologic Society of America) Member of the AIPG (American Institute of Professional Geologists)

Here is a small sampling: Mineral-rock handbook: Rapid-easy mineral-rock determination : written for anyone interested in minerals and rocks - Proctor, Peterson, and Kackstaetter;Macmillan Pub. Co. (New York and Toronto and New York) Physical Geology Laboratory e-Manual [CD-ROM], Kackstaetter, Earth Science Education LLC Colorado Front Range Self-guided Geology Field Trips, Kackstaetter,

Ph.D. in Applied Geology and Mineralogy. I am actively teaching courses in mineralogy and a variety of field courses with mineral collecting opportunities. Background in precious metal exploration.

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