Which type of aggregate's crystals are visible only with magnification greater than a standard gemological microscope's?

The crystals of cryptocrystalline aggregates are characterized by their extremely small size, typically too tiny to be seen with standard gemological equipment such as a standard microscope. This type of aggregate consists of crystals that are on the order of nanometers to several microns in size, which means that they require higher magnifications to be observed clearly.

In contrast, crystalline aggregates have larger, well-defined crystals that can typically be examined under standard magnification. Amorphous aggregates lack a defined crystal structure entirely, and microcrystalline aggregates consist of crystals that are small but not to the extent of being infinitesimal, often visible at lower magnifications. This distinction highlights the unique properties of cryptocrystalline materials, such as a lack of visible crystal faces and a homogeneous appearance under lower magnification, requiring specialized equipment for detailed study.