True diamonds have high density and should quickly sink to the bottom of the glass.
Diamonds are dense and will sink quickly, while certain imitations will sink more slowly. If your gem doesn't immediately sink to the bottom, it's likely a glass or quartz imitation. However, other imitations, including cubic zirconia, will also sink quickly.
Because loose diamonds are so dense, they should sink to the bottom when dropped in a glass of water. Many diamond fakes – glass and quartz included – will float or not sink as quickly because they're less dense.
Water testing your diamond
Get a glass full of water and simply drop your diamond into the glass. If the diamond is real, it will drop to the bottom of the glass due to the high density of the stone. If it's a fake, it will float on the surface of the water.
Gold is a very dense metal, so it will naturally sink straight to the bottom of a cup or bowl of water. On the other hand, fake gold is often made of lighter metals and will be slower to sink or not sink at all. Just like the magnet test, however, this test isn't foolproof.
Water Test
If it sinks, it is probably a real diamond. If it floats underneath or at the surface of the water, you deal with a fake diamond. Although this test might seem quite simple, it is based on the gemstone's density level. Diamonds are very dense (3.51 g/cm³) and usually outmatch the fakes in the density test.
This water test is easy if you have a loose diamond: Get a glass and fill it with water (it doesn't matter what type of water you use). Drop the diamond into the glass of water. Due to the high density of diamonds, when dropped into the water a real diamond will sink.
Carefully drop the loose stone into the glass. If the gemstone sinks, it's a real diamond. If it floats underneath or at the surface of the water, you have a fake on your hands. A real diamond has high density, so the water test shows if your stone matches this level of density.
Test your diamond using the water test
As straightforward as it sounds, fill a glass of water at home to roughly three-quarters full. Separate the stone so that it is loose, and drop it into the water. Diamonds are highly dense and a genuine gem will sink to the bottom – every time.
27, 2013 – Owners of Android phones and tablets like the Kindle Fire and Samsung Galaxy can now benefit from GIA's (Gemological Institute of America) free interactive diamond app for consumers and retailers, available in both English and Simplified Chinese.
If you turn both a diamond and a CZ upside down, the bottom of a diamond will give off the entire rainbow of color reflections, whereas CZs usually have more exclusively orange and blue flashes. This is because cubic zirconias and diamonds have different refractive indexes.
While it's true that diamonds are hard enough to cut glass, some synthetic gems can also scratch glass.
Hold it in the light to see how it sparkles.
“They do sparkle, but it's more of a gray color. If you see something with rainbow colors [inside the stone], it could be a sign that it's not a diamond.”
We all love how a diamond shines in the sunlight. Test your stone by putting it in direct sunlight and examining the colors it reflects. A real diamond will reflect both rainbow colors as well as white light. If you only get one of the two, then the diamond isn't real.
Like a high-quality natural diamond, lab-made diamonds won't get cloudy.
By holding a diamond close to a source of light, such as a flashlight, you can tell whether or not it's real. Watch closely for the shimmers of light that shine from the stone. A real diamond will reflect light easily, and provide you with a disco ball or rainbow-like display.
Diamond Fog Test
Take a big breath, as if you are trying to fog up a mirror. As you breathe onto the stone, you are looking to see if the stone clears up or remains cloudy. The moisture and heat in our breath create a fog, and if the stone is in fact a diamond, the diamond will disperse the heat very quickly.
Diamonds are naturally lipophilic and hydrophobic, which means the diamonds' surface cannot be wet by water, but can be easily wet and stuck by oil.
DON'T Wear Your Ring in Salt Water
Rose gold is especially sensitive to salt water as it will corrode much faster than traditional yellow or white gold. Salt water can also damage the overall appearance of your diamond by dulling the stones and causing them to become less shiny.
But the water itself is the main issue… Salt water can make your diamond look cloudy and the chlorine and chemicals in swimming pools and hot tubs can damage the metal of the ring itself, so always remember to take off your engagement ring.
Real gold is a heavy metal and will not float, so if your gold item floats you know it is not real gold. Also, if you notice rust or tarnishing on the item after being in water, this is also a sign it is not real gold since gold doesn't rust or tarnish.
What is Gold 750? If a gold product bears the hallmark '750', then your gold has been tested and classed as 18 carat or 75 per cent pure.