OEM cables have serial numbers on the cable and matched to the OEM packaging label. NORDOST will review and verify that cable OEM provenance first .,., it is my understanding that they won’t do alterations or repairs otherwise.
If for any reason that the authenticity cannot be easily verified , the only sure-fire to remove all doubt is to first remove the connectors and then strip back sheathing ,as thy may have to cut back the ends , and then physically examine it ,
It is also my understanding that DIY altered altered cables (b eg shortened / cut / changed connectors with non OEM done connectors) could be similarly. refused unless it was so done by NORDOST.
intuitively, if they are legit, all good …. NORDOST will prepare a quote for you to approve and prepay. Shipping cost both ways is your expense.. If any are determined to be fakes, they will be culled out badly, with the risk that they will be destroyed.