If certain insurance coverages cannot be procured from authorized insurers, such coverages, hereinafter designated "surplus lines," may be procured from nonadmitted insurers, subject to the following conditions:
1. The insurance must be procured through a licensed producer with surplus lines authority.
2. The desired coverage is necessary for the adequate protection of a risk in the State.
3. It may be written under the laws of this State by an authorized insurer.
4. The insurance is not available after diligent effort has been made to place the coverage with authorized insurers.