In the

gemstone A gemstone (also called a fine gem, jewel, precious stone, or semiprecious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks (such as lapis lazuli, opal, ...

trade, first water means "highest quality". The clarity of diamonds is assessed by their

translucence In the field of optics, transparency (also called pellucidity or diaphaneity) is the physical property of allowing light to pass through the material without appreciable scattering of light. On a macroscopic scale (one in which the dimensions a ...

; the more like

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

, the higher the quality. The 1753 edition of '' Chambers's Encyclopaedia'' states "The first water in Diamonds means the greatest purity and perfection of their complexion, which ought to be that of the clearest drop of water. When Diamonds fall short of this perfection, they are said to be of the second or third water, &c. till the stone may be properly called a coloured one." The phrase ''first water'' is also used more generally to refer to the highest quality or most extreme example of a person or thing, not just gemstones. The comparison of diamonds with water dates back to at least the early 17th century, and

Shakespeare William Shakespeare ( 26 April 1564 – 23 April 1616) was an English playwright, poet and actor. He is widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's nation ...

alludes to it in '' Pericles'', 1607.

References

{{Pericles, Prince of Tyre Diamond Quality control William Shakespeare