Answer
The MAC address by default in the BL600 and BL620 is a private static random address which is generated from a unique random serial number that is burnt into the chip by the vendor when it was manufactured. At any time you can read the MAC address by sending the module the command AT I 4.
The BLE specification allows a device to have 4 different types of MAC addresses. One of the types is the public address which comprises of a 3 byte company ID (which can be purchased from the IEEE) and a 3 byte unique number allocated by the company.
If you wish to allocate a public address, then you can do so using the one-time command AT+MAC. Once a module is allocated that address, it overrides the private static address and can never be changed although in future versions the ability to switch between public and private addresses will be exposed.