Payment of Gratuity Act, 1972

There is a separate formula for Private Employees working for Establishment covered under Payment of Gratuity Act, 1972 and Private Employees not covered.

My doubt is how to know whether the Establishment is covered under the Payment of Gratuity Act, 1972 or not when both the establishment is paying Gratuity to its employees.

Any Experts on Labour Laws can help me out?

Thanks & regards