Is Sapphire a Good Thermal Conductor?

Like other precious gems, the process of mining sapphire gems is almost the same. The sapphire crystal, however, is not found in nature. It has to be artificially manufactured. Sapphire is single-crystal aluminum oxide, sometimes having a slight ruby tint.

The ruby tint that is seen on the sapphire crystal is formed when additional chromium oxide is added. Because it is manufactured manually, the manufacturers can change its properties by modifying its ingredients. Different compositions may lead to different optical properties. Moreover, the shapes that can be formed by the sapphire crystal are also affected by the composition of the crystal.

Sapphire is commonly used as a better alternative for glass and ceramics. Because of its compositional flexibility, the crystal can be made to adhere to the needs of consumers. Generally, sapphire crystals have better optical, chemical, and physical properties that naturally make them a better option than glass and technical ceramics in many cases. In short, sapphire may be regarded as a more durable option than the materials mentioned above.

The one thing that primarily distinguishes sapphire from glass is that you cannot mold sapphire. Unlike sapphire, glass can be heated to a particular temperature and then molded into any shape you want. That is not the case with sapphire. The required shape is already created in tubes and rods, which can then further be shaped or polished as required.

The composition of sapphire

The first crystal of sapphire was made in the year 1902 by Auguste Verneuil. Since then, several methods and compositions have been used to produce sapphire crystals. The aim of the process is to turn aluminum oxide into a single crystal with zero porosity.

The state of zero porosity is achieved when the aluminum oxide is treated with extreme heat and extreme pressure. Sapphire crystals can range from yellow, purple, green, and pink to blue colors. They are often found colorless, as well. The color of the sapphire depends upon the Iron, Titanium, and Chromium Oxide content in the composition.

Thermal conductivity and other physical properties

The thermal conductivity of sapphire is 46.06W/m.K. With such a high thermal conductivity, sapphire can allow heat to pass through it at a higher rate than glass, exactly 40 times higher. This makes sapphire a better alternative than glass and ceramics because heat can easily transfer from one body to another if there is sapphire present between the bodies. It is sometimes used in construction as well for places that require a high transfer of heat between them.

Sapphire has a melting point of about 4000°C. That makes it sustainable in extremely high temperatures. One of the most beneficial properties of sapphire over glass is the purity and transparency of sapphire crystals. For that reason, it can be used as a viewing window in places with harsh conditions such as extreme pressure, temperature, and vacuum applications.

The only material in existence that is harder than sapphire is diamond. Sapphire is a scratch-less and durable transparent crystal, which is the reason for many smartphone companies choosing sapphire as it is about four times stronger than a gorilla glass screen. The structural integrity of things composed of sapphire is high because of their extreme durability.

The electrical resistance of sapphire is high as well, which makes it a good choice in buildings where there is a high risk of electrical damage. The high electrical resistance adds up to the already great durability and sustainability of the material and makes it one of the strongest and toughest materials in the world.

Uses of sapphire

Because of its tough properties, sapphire is widely used throughout the world. Some of its uses are as follows.

Sapphire is used in jewelry, adding up to the gold or silver necklaces and earrings.

Sapphire is used to create watch crystals. It has been widely used in watches for many years, specifically in Swiss timepieces. Moreover, it is even used today in smartwatches.

Sapphire is used in high-durability windows.

It is also used to make electronic wafers.

Sapphire is used for making scientific instruments.


The thermal conductivity of sapphire mainly depends on the temperature. Considering the room temperature, it has a high thermal conductivity in comparison with stainless steel. The thermal property of this element makes it useful for a wide variety of purposes, some of which are discussed above. What other properties, except for the thermal conductivity of sapphire, do you think make it valuable?