From my experience and in my opinion (please correct me if any of the below statements is incorrect):
- There are no suppliers selling Apple original parts for Apple devices (except may be some Mac batteries), since Apple only allows Apple Stores and Apple Certified Service Centers to fix and/or replace Apple devices,
- iDevices orignal replacement parts can be found ONLY at Apple Stores, NOT at Apple Certified Service Centers.
- Original Mac parts (Apple parts but not iDevices parts) CAN be obtained by Apple Certified Service Centers, but the service centers have to justify every part that they order by matching it with the specific device that needs repairing.
In other words, Apple very tightly controls the production, distribution, and use of Apple original spare parts, and we cannot find them in the free market for sale.
- I believe the only other way to obtain original parts other is from Apple devices that have been disassembled and sold for parts.
- In summary, don't waste time testing your parts to see if they are OEM, they ARE NOT in my opinion. You'd better just stick with a supplier of quality parts if you find one that sells them at an acceptable cost.