Properties -> Material -> IOR Values
List size: 247
To use it, simply type your query into the search box, example: “oxygen”, and possible matches will automatically be listed, and further narrowed the more you type. Once you’ve found a match, clicking it will return its IOR value in the “IOR” field. If “Copy to SSS” is enabled (which it is by default), it will automatically change the value of the Subsurface Scattering IOR to this value, but only if Subsurface Scattering is also enabled.
NOTE: I created the list of IOR values from online sources. If you notice any errors, or can suggest additions for the list, please leave me a comment.
A wiki page would have been created, and this uploaded sooner, but currently there is no “Materials” category in the Wiki catalog. I’ve asked if I would be allowed to add this category, but I’ve not heard back from anyone yet. If I’m allowed to, I’ll do so and make a page for this addon. I’d rather not do it without permission!
I hope you find it useful!