As with enlisted, we follow the US Army for officer's insignia, ignoring ranks we do not recognize. Our Chief Warrant Officer is equivalent to an Army CW2, our Senior Chief Warrant officer to the CW4. We do not have an equivalent to the CW3 or CW5.
For metal pin-on insignia, we prefer the "subdued" forms of insignia (black in place of silver and brown in place of bronze). Most vendors of insignia provide an option for normal or subdued colors.
We attempt to provide insignia when an officer/NCO is commissioned/promoted. If the insignia is lost, it is the volunteer's responsibility to replace it. If you are promoted, it is considered an honor and courtesy to pass your old insignia down to a newly promoted volunteer.