can diamonds float in water


Diamond is a pure form of carbon that occurs as a hard and, most times, transparent substance. They are gemstones and can be found deep down in the earth’s crust. They have the highest thermal conductivity and hardness of any known substance that exists in nature. Diamonds have a high specific gravity and also high density, which is why they are very hard. Another reason for the hardness of diamond is the nature of arrangement of the carbon atoms that make up diamonds. Carbon atoms are in excess in diamonds and are arranged in a tetrahedral bond. These tetrahedral bonds are very strong.

Diamonds are arguably the most popular gemstone on earth. They are highly priced and are considered as precious gems. Diamonds are used for making jewelry pieces for personal adornment and bodily embellishment. They are mostly worn by rich folks because of their high price. Due to the popularity of diamonds, people of lesser means also seek to own diamond pieces of their own or at least something that looks like diamonds. For this reason, diamonds are imitated and sold at prices that are relatively lower than the price of real diamonds. Imitated diamonds are referred to as “synthetic diamonds“, “diamond simulants” or “fake diamonds”. So can diamonds float in water?


Fake diamonds are cheap materials used in place of diamonds. They generally have different chemical compositions from diamonds and are made from both natural and synthetic materials. Imitated diamonds are not synthetic diamonds. While imitated diamonds are not real diamonds, synthetic ones are. Synthetic diamonds identify as real diamonds, just like natural diamonds. Fake diamonds are cheaper and less hard than real diamonds.

How to tell a real diamond from fake ones?

Diamond simulants are designed in such a way that it would not be so easy for someone who is not a gemologist or jeweler to tell that they are not real diamonds. Real diamonds can be differentiated from fakes ones by taking note of some of the properties unique to them. These properties include:

  • Real diamonds do not scratch easily

Diamonds are very hard materials. The only substance than can scratch a real diamond is another diamond. Diamond simulants can easily be scratched with a sandpaper or knife. This is because they are not as hard as real diamonds.

  • Real diamonds do not fog up with breathed upon

Diamonds are good conductors of heat and hence, good dispersers of heat. When hot air is breathed on a diamond piece, the fog developed dissipates almost immediately. ‘Diamonds’ that take long to disperse the fog formed on them when breathed upon are not real diamonds.

  • Real diamonds are heat resistant

Diamonds are resistant to high heat. This is due to their strength. When diamond is exposed to heat it would disperse quickly and won’t be affected by the change in temperature. To tell if a supposed diamond is fake burn with direct heat from a lighter for about a minute, if it melts then it is definitely not a diamond piece. Some fake diamonds may not melt in that amount of heat. So, to test further, after heating the stone for about a minute drop it directly in cold water. Most diamond stimulants would crack, break or even shatter when in this cold water. 

  • Real diamonds have high density and hence cannot float on water.

Real diamonds are heavy i.e. they have high relative density. Due to the high density of diamonds, when put in water, they sink. One way of identifying a real diamond from a fake one is by putting it in water, if it sinks then it is fake, but if not, it is probably a real diamond. Although it is important to note that not all fake diamonds sink in water, some diamond simulants e.g. Cubic zirconia, are denser than water, so when put in water, they sink.

Diamonds cannot float in water!


As stated in the previous section of this article, the main reason why diamond cannot float on water is due to its high relative density. It is also known as Specific gravity.

Specific gravity of Diamond

Specific gravity is how dense a material is in relation to another material. In this case, how dense diamond is in relation to water, since we are considering whether or not diamond floats in water. At normal room temperature, diamond is over 3.5 times denser than water. If diamond is dropped in a glass of water, because of its high density will go straight to the bottom of the glass. This then means that if you lose your diamond piece while swimming in a river, you’d most likely never get it back. 

There are some gemstones that are denser than diamond. For instance the specific gravity of ruby, zircon and sapphire is around 4.0 (that means they are 4 times denser than water). When these materials are dropped in water alongside diamond they will sink before the diamond will. 

Specific gravity is a property through which diamonds and other gemstones can be identified. For instance, Zircon which is a diamond simulant has a specific gravity between 4 and 7. So, if diamond and Zircon is put in a glass of water, it is expected than the zircon gets to the bottom of the glass before the diamond. Also, considering a diamond simulant, colorless quartz, with a specific gravity of 2.6, if it is put in a glass of water at the same time with diamond will get to the bottom of the glass later than diamond.

There are some liquids inside which diamonds can float. Those are liquids with higher density than diamonds i.e. those with specific gravity of more than 3.5 (relative to water), e.g. mercury (specific gravity, 13.6), galinstan (specific gravity, 6.4) etc.


Diamonds do not float in water but can float in liquids denser than it, the most common being mercury. The specific gravity of water, explaining its floatation property in water can be used to identify real diamonds. 

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