ISO 17025 - Traceability Questions

Hi, I am basing my answer on the assumption you are a testing, not a calibration laboratory.

You asked

1. If we measure another set of calibration lenses in house with our now calibrated lab metrology device, can we claim the power of these lenses are NIST Traceable? (no longer requiring the use of another external provider)

Yes, provided that you establish and maintain metrological traceability through an unbroken, documented calibration chain, and evaluate the associated measurement uncertainty. According to ISO 17025, metrological traceability requires you to link measurement results to a reference (e.g., NIST) through a documented, unbroken chain of calibrations, each contributing to measurement uncertainty.

Therefore, if your metrology device is calibrated using traceable standards, the calibration covers the required range, and measurement uncertainty is evaluated and controlled, then the values you assign to lenses can be claimed as traceable to NIST.

You also asked

2. If so, my assumption here is that we would need to confirm through documentation/audit of the original external lab and target provider to confirm that the chain is unbroken - all certificates/claims are valid etc.

What you need to do is ensure the competence and suitability of external providers, but you are not required to audit the full traceability chain back to NIST. This is typically achieved by using accredited laboratories or evaluating non-accredited providers based on technical competence.  Yes, check that they are accredited or competent (through proven records) and that their certificates include traceability and report uncertainty, and that they retain documented evidence supporting the traceability claim.