4 Carat Sapphire (Cushion, 8.79×8.79mm, Blue)

Color:

blue

actual size

Actual size is set for screen

How big is a 4 carat cushion-cut Sapphire?

It depends on the cut parameters and length-to-width ratio, but a typical size of a 4ct square cushion-cut Sapphire would be around 8.79×8.79 mm (±6%). Check how big it looks on a ring and finger.

Ring:

Gold
Platinum

Skin tone:

Pale
Light
Medium
Dark

Ring width: 3.0 mm

Saved...

64 mm

Your settings
Ring	Gold
Skin tone	Light
Ring diameter	16.9 mm
Ring width	3.0 mm
Finger length	64 mm
Finger coverage	53 %

Saved...

Ring diameter: 16.9 mm

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Additional Info

Sapphire got its name from the Greek word "sappheiros", which means "blue stone". Today, most people still associate Sapphires with the color blue, however, any gemstone quality Corundum that is not red (Ruby) is actually called Sapphire.

Where to buy?

For certified gemstones, high-end gemstone jewelry, and birthstone jewelry, see Blue Nile

Gem Details

Name:	Sapphire
Mineral Group:	Corundum
Shape:	Cushion
Chemical Formula:	Al₂O₃
Crystal Structure:	Hexagonal
Hardness:	9
Specific Gravity	4
Carat weight:	4 ct
Gram weight:	0.8 g (0.0282 ounces)
Points:	400 pts
Length:	8.79 mm
Width:	8.79 mm
Est. face-up size:	69.54 mm²
Volume:	200 mm³
Length-to-width ratio:	1
Refractive Index:	1.76 - 1.77
Luster:	Vitreous to adamantine
Wearability:	Excellent
Care Instructions:	No special or unusual care
Color:	Sapphire can be found in the following colors:
Birthstone:	Sapphire is a birthstone for the month of September

Popular comparisons:

About Sapphire Specific Gravity

Sapphire has a specific gravity of approximately 3.95 - 4.05, with 4 being a generally accepted standard average for gem-quality material.

For all the Sapphire size calculations on this website, the specific gravity of 4 is used.

To learn more about it and why it matters, and to compare densities of all the gemstones on one page, click here.

Ring & Finger Simulator

Use the simulator on this page to play around with different ring and finger configurations.

To select a different gemstone, shape, color or size, or to compare two gems side-by-side, use the form at the top of the page. Comparison example: 4ct Sapphire vs Topaz (Cushion Cut)

If you want to compare cushion-cut Sapphire sizes from 0.25 to 40ct on one page, see Cushion Cut Sapphire Size Chart

In order to view real-world sizes on your screen, ensure that the actual size is set to your device screen size (diagonal in inches).