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Ishizuka Glass CRYSTERNA

CRYSTERNA, a High-Strengthened glass

Marubeni is proud to introduce high-strenghtened glass by it's manufacturing partner, Ishizuka Glass Co. CRYSTERNA is a special glass with a compressed stress layer that enables superior durability to the surface of the substrate.

Glass easily breaks or scratches when a strong force is physically applied to it; it has an inherent characteristic of having a weak tensile strength. By adding compressed stress to its surface, high-strengthened glass CRYSTERNA can withstand an amount of force that does not exceed the compressed stress that is intentionally added to it.

CRYSTERNA is strengthened through chemical tempering. Ishizuka uses an ion exchanging method for the chemical tempering of its glass products. This method allows the glass surface to maintain a slightly compressed stress layer by exchanging sodium ions (Na+) in the glass surface layer with potassium ions (K+) through thermally assisted chemical tempering, thus greatly enhancing the strength of the glass.

Developed for applications that require glass with superior strength, Ishizuka boasts a top market share of glass used in watch coverglass applications in the Japanese market. CRYSTERNA is presently used in watch coverglass as well as other applications not only in Japan but around the world.


With a strength greater than sapphire, CRYSTERNA can be used in applications where thin glass is desirable.

As deep compressed stress layer on the surface of the glass obtained, at the time of ion exchange, the hardness of CRYSTERNA is superior than other glass.

CRYSTERNA maintains an excellent strength performance based on a wide range of strenghtening treatments.

The mechanical processability is the same as common glass and therefore there there are no associated cost premiums.

Chemical Tampering
Characteristics of "CRYSTERNA"
Specific gravity 2.51 g/cm3 JIS C 2141
Chemical durability 0.28 Na2Omg ASTM C 225
Refractive index 1.52 nD JIS K 7105
Strain point 511 C. JIS R 3103
Softening point 708 C. JIS R 3103
Expansion (a) 8.7 10-6/C JIS C 2141
Bending strength 863 MPa JIS C 2141
Vickers hardness (Hv) 640 300g,15sec JIS C 2141
Young's modulus 7 104 MPa JIS R 3103
Surface compression 588 to 980 MPa Measured by"FSM-60"
Surface compression layer 20 m


Static Pressure Strength

Impact Strength (Drop Strength)

Comparison with among material
Materials CRYSTERNA White
sheet glass
sheet glass
Bending strength
863 637 618 686
Vickers hardness (Hv)
300g 15sec
640 570 570 1200
Surface compression
785 588 549 -
Surface compression layer m 20 10 13 -

Product specification
Article No. Plate
thickness (mm)
length (mm)
width (mm)
Number of
IG315 1.5 0.2 500 20 160 15 70
IG323 2.3 0.2 160 15 45
IG328 2.8 0.2 150 15 40
IG335 3.5 0.2 140 15 35

  1. Cover glass for Watches
  2. Cover glass for Cell phones
  3. Cover glass for Digital camera (lens and display)
  4. Cover glass for small displays (GPS, Radio, etc)
  5. Cover glass for other applications
Contact Address

For more information on CRYSTERNA High-Strengthened Glass by Ishizuka, please contact Marubeni Sunnyvale and we will send you a full brochure and information packet.