Omega Speedmaster: Hesalite vs Sapphire

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At some point in your life as a watch collector, you will be faced with the decision to buy an Omega Speedmaster. It’s on the list of new and established collectors for many reasons –timeless design, history and heritage, and impressive reputation, among others.

Today, Omega offers the classic Speedmaster Professional MoonWatch in two configurations: one with Hesalite crystal and another with a Sapphire crystal. This usually presents a dilemma, especially for first-time Speedy owners.

Hesalite is an advanced form of acrylic – a versatile, transparent plastic that has outstanding strength, stiffness, and optical clarity.

Its use dates back to the 1840s and it’s found anywhere from polishes to contact lenses. Since it’s a man-made substance, it can be easily worked into shapes as needed; and tends to crack instead of shatter into pieces when hit by impact. This made it an ideal material for watches, as it keeps its shape when dropped.

The original Omega Speedmaster MoonWatch had a Hesalite crystal. While the newer, harder sapphire crystals were already available then, it had the propensity to shatter like glass, which presented risks in space.

The Hesalite crystal was retained on the Speedy when NASA selected it as the official timekeeper of the Apollo program.

One disadvantage of Hesalite is that it is more prone to scratches compared to glass or sapphire. Light marks can be polished out with a mild abrasive, but continuous damage can blur out the crystal and affect legibility.

It is cheaper than sapphire crystal however, in case there is a need to replace it.

Sapphire is best known to the general public as the blue gem; and the sapphire used for watch crystals is a variant of the same mineral that forms the gem. The mineral called corundum is the second hardest mineral on the planet, next only to diamond.

The corundum used for watch crystals are manufactured in laboratories and are about four times tougher than acrylic. It’s also extremely scratch resistant. This is definitely its edge over hesalite, but this toughness presents a few problems, as well.

While hesalite can be formed into different shapes with ease, sapphire can only be cut and polished from a solid block, into its finished shape. This gives the Speedmaster sapphire crystal its thicker, more artificial looking dome. Its thick edge also gives the crystal a white “halo” around its circumference.

Lastly, the tricky process of shaping sapphire crystal also makes it more expensive.

MAKING YOUR CHOICE: HESALITE vs SAPPHIRE