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Specific Gravity
Definition of Specific Gravity
Specific gravity is a measure of the density of a mineral or in this case optical lens material.
It is derived from the density of the lens material divided by the density of
water. Since water's density equals 1 gram per cubic centimeter (at specific conditions),
then a mineral's specific gravity (SG) would also correspond to a mineral's density as expressed in grams per cubic centimeter (g/cm3).
Since a glass lens has a specific gravity of 2.54, then it is nearly three times as dense as water as well as Trivex.
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Table Of Various Materials by Wieght
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Index of Refraction
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Specific Gravity
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Trivex (1.53) |
1.11 |
Hoya (1.56) |
1.20 |
Polycarbonate (1.59) |
1.21 |
Sola (1.53) |
1.21 |
Plastic (1.50) |
1.32 |
Essilor (1.60) |
1.34 |
Nikon (1.60) |
1.34 |
Signet (1.60) |
1.34 |
Sola (1.60) |
1.34 |
Varilux (1.60) |
1.34 |
Pentax (1.66) |
1.35 |
Essilor (1.67) |
1.35 |
Hoya (1.67) |
? |
Nikon (1.67) |
1.35 |
Index of Refraction
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Specific Gravity
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Kodak (1.67) |
1.35 |
Varilux (1.67) |
1.35 |
Essilor (1.56) |
1.36 |
Nikon (1.56) |
1.36 |
Varilux (1.56) |
1.36 |
Seiko (1.67) |
1.36 |
Optima (1.66) |
1.36 |
Hoya (1.70) |
1.41 |
Essilor (1.74) |
1.46 |
Crown Glass (1.52) |
2.54 |
Glass (1.60) |
2.60 |
Glass (1.70) |
3.20 |
Glass (1.80) |
3.66 |
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The Spectacle Shoppe, Inc., 306 N Rock Road, Ste 10, Wichita, KS 67218, 316-686-6111, 800-651-8472, Fax 316-686-7665
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