Hardlex type is one type of glass that was first developed by Seiko. Broadly speaking, hardlex is a type of mineral glass that has been processed further, so that it has a harder level of hardness than mineral glass in general, but is still under the sapphire crystal. So that it can be said, hardlex is a type of glass that is between the mineral glass and sapphire crystal. One of the watches that use hardlex glass is Seiko sbdx001. In the meantime, check out the recommended tag heur watch as well.
However, the use of sapphire crystal is still more reliable when compared to mineral glass. One example of a watch that uses Sapphire Crystal is the Seiko SBDX 014 series.
Apart from the price side where sapphire cristal identic with luxury watches because indeed the cost of making sapphire crystal is higher when compared to mineral glass. This type of sapphire crystal can make your watch look more durable.