hi! how do i detemine whether a fiber is MM or SM? Will it work if the connector is SX type but the fiber patch cord is single mode type? or will it work if the connector is LX but the patch cord is multimode?

We do have quite a few fiber cables that has the 62.5um printed on the cable surface, which is single mode. But i'm not too sure about those that do not have any spec printed on the cable. So how do i detemine whether is it single mode or fiber mode in this case?

Thanks.