Ruby exhibits identical properties to those of Sapphire. Small amounts of impurities give Ruby a red colour.



Density ρ

3.98 g/cm³ at 20 °C

Porosity Vvoid

0 %

apparent porosity

Water absorption, equilibrium cwater,equib

0 % at 20 °C


Compressive strength Rmc

2100 MPa at 20 °C

Elastic modulus E

350 - 390 GPa at 20 °C

Hardness, Knoop, HK2 HK2

2000 [-] at 20 °C

Hardness, Vickers HV

2500 - 3000 [-] at 20 °C


Coefficient of thermal expansion α

5.8E-6 1/K at 100 °C

Max service temperature, continuous Tmax,cont

1800 - 1950 °C

Melting point Tm

2050 °C

Specific heat capacity cp

750 J/(kg·K) at 25 °C

Thermal conductivity λ

35 - 40 W/(m·K) at 20 °C


Dielectric constant εr

7.5 - 11.5 [-] at 20 °C

Dielectric strength EDS

15 - 50 kV/mm at 20 °C

Electrical resistivity ρel

1.00E+12 Ω·m at 25 °C

Technological properties



Corrosion properties

Good chemical resistance to: Acids (concentrated and diluted), alkalis, halogens, metals


Useful optical transmission range: 150-5500nm

This material data has been provided by Goodfellow.

All metrics apply to room temperature unless otherwise stated. SI units used unless otherwise stated.
Equivalent standards are similar to one or more standards provided by the supplier. Some equivalent standards may be stricter whereas others may be outside the bounds of the original standard.