The Philips Ultralume 3500 K fluorescent illuminant has no CIE standardized version and for this reason natific is using the more common U3500 version in our products.

Natific has confirmed this with the brands we work with and they expect this version to be used for quality assessment.

Natific QcExpress will calculate with this version of the illuminant, but if you are using a third-party software like Tools or iQC, please make sure you select the correct illuminant:


Select U3500 10 Deg.

DO NOT use UL35, which will give different results.


Select CIE Illuminant Table 6.

Only U35-10 is available in iQC by default, which will produce slightly different results compared to natific products.

Contact x-rite support if you need more information on how iQC handles Ultralume 3500.