OK. So putting the voodoo to one side, as far as I can see, 'Sonic Link' changed their name to 'Black Rhodium' in the early 00's. Assuming (possibly a big assumption) that all they did was sprinkle some marketing fairy dust and change the names of their products, then the current product in their range that seems to be the same as yours is 'Jive Biwire'
Ignoring the choice of company name (rhodium is not actually a great conductor), the Jive Biwire is 4 x 1.5mm^2 tin plated copper conductors. If you have access to a micrometer, you could measure the strand diameter of your cables and figure out the total cross sectional area to see whether it is 1.5mm^2 - which may help identify your product.
Unless you are bi-amping, then biwiring is generally a bad idea. If you are not bi-amping, the best upgrade you could make would be to connect the respective positive and negative conductors together at both ends of the cable (red to red and black to black) to parallel up the conductors. If you have removed the shorting plate on your speakers, put it back.
This will take your 1.5mm^2 (a bit thin for long runs) up to 3mm^2 which will be more than adequate.
Good luck.