{"id":7017,"date":"2019-01-02T06:00:30","date_gmt":"2019-01-02T11:00:30","guid":{"rendered":"http:\/\/www.jewelry-secrets.com\/Blog\/?p=7017"},"modified":"2019-01-02T09:27:59","modified_gmt":"2019-01-02T14:27:59","slug":"how-are-gemstones-measured-mm-vs-carats","status":"publish","type":"post","link":"https:\/\/www.jewelry-secrets.com\/Blog\/how-are-gemstones-measured-mm-vs-carats\/","title":{"rendered":"HOW ARE GEMSTONES MEASURED? MM VS CARATS"},"content":{"rendered":"
\"Gemstone<\/div>\n

Gemstones are an interesting topic when it comes to measurements<\/strong>. Sometimes you’ll see gemstones listed as millimeter (MM) size (often misspelled as milimeter<\/strong>), like 6 x 4mm, and other times you’ll see gemstones listed as a carat weight, like 1.00 carats.<\/strong><\/p>\n

What Gives?<\/h2>\n

\nWhat makes gemstones, like sapphire, ruby & emerald<\/strong>, so different that they’re measured differently? Let’s find out…<\/strong><\/p>\n

Carats…<\/h2>\n

\nGemstones have many unique attributes that make them so different from diamonds<\/strong>. When it comes to diamonds, most people know and understand how diamonds are weighed. They’re used to carats and carat sizes<\/strong> and can easily relate to them.<\/p>\n

\nBut, when it comes to gemstones they have no clue<\/strong>. The biggest reason why gemstones are measured differently than diamonds are quite simple:<\/strong><\/p>\n

They don’t weight the same.<\/h2>\n

\nMore accurately, their specific gravity is different.<\/strong> Diamond’s specific gravity (how much it weighs in water) is 3.52. Some gemstones like amethyst for example are lighter weight and have a specific gravity of 2.66. Sapphire on the other hand is 4.0. All gemstones weigh differently.<\/strong><\/p>\n

\nSo a one carat (1.00) diamond will not look the same<\/strong> size as a one carat amethyst or a one carat sapphire. So if all gemstones were weighed in carat sizes, they would all look like different sizes.<\/strong><\/p>\n

\nIt would get very confusing, very fast.<\/strong><\/p>\n

\nPeople may think that they’re getting a big gemstone, only to find out it looks small<\/strong>.<\/p>\n

\nCarat weights in gemstones just don’t work well. Jewelers only sell them that way because people are accustomed to shopping for carat weights. It just makes sense.<\/strong><\/p>\n

Millimeter sizes:<\/h2>\n

\nThe correct way to buy gemstones is by millimeter size<\/strong> like 4 x 6mm, or 5 x 7mm. That way, a 4 x 6mm sapphire will actually look the same size as a 4 x 6mm amethyst, no matter what the weights are.<\/p>\n

\nPlus, most mountings sold for gemstones are set up for millimeter sizes<\/strong>, not carat weights. Just look in any jeweler’s catalog and you’ll see. A mounting like a mother’s ring for example may call for gemstones that measure 2.5mm each.<\/p>\n

Cut:<\/h2>\n

\nNot only are gemstones weighed differently than diamonds, but gemstones are cut differently as well<\/strong>. Most gemstones are much deeper than a diamond is. In fact, gemstones need to be cut deeper to help bring out their vivid color<\/strong>. If a gemstone was cut like a diamond, chances are it would appear light in color and even look transparent<\/strong>. They’ll lack those intense dramatic hues that gemstones are known for.<\/p>\n

\nSo when it comes to shopping for gemstones, forget about carat sizes<\/strong>, that’ll do you no good. Look at the millimeter sizes and the intensity of the color instead. In most gemstones, the darker the color, the better.<\/strong><\/p>\n

\nHere’s a chart that compares the millimeter sizes of diamond and sapphire to their corresponding carat weights.<\/p>\n

Compare weights:<\/h2>\n

\n\"Millimeter<\/p>\n

\nNow lets look at standard gemstone millimeter sizes for oval stones versus their carat weights<\/strong> (sizes will vary slightly depending on the gemstone’s specific gravity).<\/p>\n

Oval gemstones:<\/h2>\n\n\n
\n
    \n
  • 5 x 3 mm = .25 ct<\/strong><\/li>\n
  • 6 x 4 mm = .50 ct<\/strong><\/li>\n
  • 7 x 5 mm = 1.00 ct<\/strong><\/li>\n
  • 8 x 6 mm = 1.50 ct<\/strong><\/li>\n
  • 9 x 7 mm = 2.50 ct<\/strong><\/li>\n
  • 10 x 8 mm = 3.00 ct<\/strong><\/li>\n<\/ul>\n<\/td>\n
\n
    \n
  • 11 x 9 mm = 4.00 ct<\/strong><\/li>\n
  • 12 x 10 mm = 5.00 ct<\/strong><\/li>\n
  • 14 x 10 mm = 6.00 ct<\/strong><\/li>\n
  • 14 x 12 mm = 8.00 ct<\/strong><\/li>\n
  • 16 x 12 mm = 10.5 ct<\/strong><\/li>\n
  • 18 x 13 mm = 14.2 ct<\/strong><\/li>\n<\/ul>\n<\/td>\n
\n