Literature observation
A Chinese sapphire cutting study describes using a looped diamond wire with 0.70 mm diameter and 4 m length to cut a 53 mm sapphire cylinder, with the cut completed in about 30 minutes under that experiment.
The paper studies how cutting parameters influence wafer surface roughness and discusses the cutting mechanism.
Practical caution
This result should not be used as a universal production promise. Sapphire orientation, diameter, machine stiffness, coolant, wire condition, and surface requirements can change the outcome.
For sapphire, the safest commercial route is test cutting followed by parameter refinement.