search
  • Inicie Sesión
    Registrarse
  • Servicio al cliente sólo en inglés

    Número gratuito - EE. UU. & Canadá únicamente:
    1-800-464-1640

    Internacional:
    +66-39303404

  • Cambiar idioma
  • USD

Buying Gemstones for Jewelry: Understanding Gemstone Sizes

For many people, gemstone sizes can be very confusing, not only for those who are unfamiliar with the metric system, but also for those who don't completely understand the exact format in which gemstones sizes are described and provided. The internationally recognized unit of measurement for gems and jewelry, including diamonds, colored stones and jewelry findings is always given in millimeters, usually rounded to the nearest two decimal points.

For our US customers, the following inch to millimeter conversion table may be helpful when buying gems by size for your jewelry needs:

Inches in Fractions Inches in Decimals Millimeters Everyday Item of Approximate Size
1" 1.00" 25.4 mm Diameter of US quarter
7/8" 0.875" 22.225 mm Diameter of US nickel
3/4" 0.750" 19.05 mm Diameter of US penny
11/16" 0.6875" 17.4625 mm Diameter of US dime
5/8" 0.625" 15.875 mm Inside diameter of US ring size 5
9/16" 0.5625" 14.2875 mm Inside diameter of US ring size 3
7/16" 0.4375" 11.1125 mm Half the diameter of a US nickel
3/8" 0.375" 9.525 mm Thickness of an iPhone 4
5/16" 0.3125" 7.9375 mm Thickness of an iPhone 5
3/16" 0.1875" 4.7625 mm Thickness of a juice box straw
1/8" 0.125" 3.175 mm Thickness of 2 stacked US pennies
1/16" 0.0625" 1.5875 mm Thickness of a US penny
3/64" 0.0394" 1.00 mm Thickness of a CD
1/32" 0.03125" 0.79375 mm Thickness of a credit card

The format used to describe gemstone sizes can also vary depending on the shape of the specific stone. For round gemstones, usually two dimensions are detailed; diameter and depth. For ovals and fancy shapes, gemstones sizes are described using three dimensions; length, width and depth.

Gem buyers should also be aware that gemstones are rarely cut with perfect symmetry, and depending on where a stone is actually measured from, its size may be given as differing values. Thus, it's highly recommended to allow for some variance in regard to exact millimeter sizes when buying colored gemstones for your jewelry settings.

How Big Will My Gemstone Look?

The picture below may be helpful when deciding how big or how small a gemstone you require for your jewelry. This image shows an outline of how a 6.5 mm round stone may look when set in standard ring sizes. A 6.5 mm stone may look large in delicate jewelry designs, but in chunkier designs such as a men's rings, a 6.5 mm stone will appear much smaller than you might expect.

Gemstone size comparison chart
A 6.5 mm gemstone in comparison to standard USA ring sizes (inside diameter).
  • Primera publicación: July-28-2014
  • Última actualización: July-09-2019
  • © 2005-2020 Reproducción (texto o gráficos), sin el consentimiento expreso por escrito de GemSelect.com (SETT Compañía Ltda.) es estrictamente prohibida.
More Shapes
Piedras Preciosas Populares
  • Zafiro
  • Esmeralda
  • Rubí
  • Aguamarina
  • Circón
  • Ópalo
  • Topacio
  • Turmalina
  • Granate
  • Amatista
  • Citrina
  • Tanzanita
Todas las gemas (145)
A B C D E F G H I J K L M N O P R S T V Z Á Ã Ó
  • Aguamarina
  • Aguamarina Ojo de Gato
  • Amatista
  • Amazonita
  • Ametrina
  • Amolita
  • Andalucita
  • Andesina Labradorita
  • Apatita
  • Apatita Ojo de Gato
  • Augita ojo de gato
  • Azurita Druzy
  • Berilo
  • Berilo Dorado
  • Calcedonia
  • Calcita
  • Charoita
  • Chrysocolla
  • Cianita
  • Circón
  • Citrina
  • Clinohumite
  • Coral
  • Coral Fósil
  • Cornalina
  • Crisoberilo
  • Crisoprasa
  • Cromodiópsido
  • Cuarzo
  • Cuarzo Ahumado
  • Cuarzo Fresa
  • Cuarzo Limón Estrella
  • Cuarzo Místico
  • Cuarzo Ojo de Gato
  • Cuarzo Rosa
  • Cuarzo Rosa Estrella
  • Cuarzo Rutilado
  • Cuarzo con marcasita
  • Diamante
  • Diásporo con Cambio de Color
  • Diópsido Estrella
  • Doblete de Ópalo
  • Druzy Amethyst
  • Enstatita
  • Escapolita
  • Escapolita Ojo de Gato
  • Escolecita
  • Esfalerita
  • Esfena
  • Esmeralda
  • Esmitsonita
  • Espectrolita
  • Espinela
  • Fluorita
  • Fluorita con Cambio de Color
  • Fucsita con Rubí
  • Gemas de estrella
  • Gemas de jade
  • Geoda ágata
  • Granate
  • Granate Alamandino
  • Granate Demantoide
  • Granate Espesartina
  • Granate Estrella
  • Granate Grossularita
  • Granate Hesonita
  • Granate Malaya
  • Granate Piropo
  • Granate Rodolita
  • Granate Tsavorita
  • Granate con Cambio de Color
  • Grandidierita
  • Hematita
  • Hemimorfita Druzy
  • Hiddenita
  • Howlita
  • Idocrasa
  • Iolita
  • Jadeíta
  • Jaspe
  • Kornerupina
  • Kunzita
  • Labradorita
  • Lapislázuli
  • Larimar
  • Madreperla
  • Malaquita
  • Mali Granate
  • Matriz Ojo de Tigre
  • Maw-Sit-Sit
  • Morganita
  • Nuummite
  • Obsidiana
  • Obsidiana Copo de Nieve
  • Ojo de Gato Actinolita
  • Ojo de Halcón
  • Ojo de Tigre
  • Ojos de gato
  • Peridoto
  • Perla
  • Piedra de Luna
  • Piedra de Luna Arco Iris
  • Piedra de Luna Estrella
  • Piedra de Luna Ojo de Gato
  • Piedra de Sangre
  • Piedra del Sol
  • Piedra del Sol Estrella
  • Pietersita
  • Pirita
  • Pirita Arco Iris
  • Prehnite
  • Rodocrosita
  • Rubellita Turmalina
  • Rubí
  • Rubí Estrella
  • Rubí-Zoisita
  • Serafinita
  • Serpentina
  • Silimanita
  • Silimanita Ojo de Gato
  • Sodalita
  • Sugilita
  • Tanzanita
  • Topacio
  • Topacio Imperial
  • Topacio Místico
  • Turmalina
  • Turmalina Cromo
  • Turquesa
  • Variscita
  • Venturina
  • Zafiro
  • Zafiro Estrella
  • Zafiro con Cambio de Color
  • Ágata
  • Ágata Dendrítica
  • Ágata de Fuego
  • Ópalo ojo de gato
  • Ópalo
  • Ópalo Boulder
  • Ópalo Chocolate
  • Ópalo Moss
  • Ópalo Negro
  • Ópalo de Fuego
  • Ópalo en matriz
Main Categories
  • Nuevas llegadas
  • Lotes de gemas
  • Las Piedras Preciosas Calibradas
  • Piedras preciosas por pieza
  • Gemas de grado superior
  • Pares Emparejados
  • Gemas Corte Cabujón
  • Drilled Gems, Briolettes and Beads
  • Piedras zodiacales
  • Las Tallas de Piedras Preciosas
  • Gemas elegantes
  • Gemas de estrella
  • Zafiro sin Calefacción
Servicio al cliente sólo en inglés

Número gratuito - EE. UU. & Canadá únicamente:
1-800-464-1640

Internacional:
+66-39303404

Ahorra Dinero
No hay gastos de envío para artículos adicionales
$8.90 envío en todo el mundo

Update Translation
 
Current Value
New Value
GemSelect Gemstones
X Cerrar ventana
Colored Gemstones
X Cerrar ventana
Colored Gemstones
X Cerrar ventana
Colored Gemstones
Tamaño y peso

Gems are always measured in Millimeter (mm)

Dimensions are given as;
length x width x depth,
except for round stones which are;
diameter x depth

Select gems by size, not by weight!
Gem varieties vary in density, so carat weight is not a good indication of size

Note: 1ct = 0.2g

Size Comparison Chart