Per the manufacturer PPG, starphire or low iron has generally the same hardness as regular glass. People hear "low iron" and they instantly think it is softer. One wacko on a post claimed he could scratch starphire like acrylic with his fingernail but unless he is wolverine, he is full of crap. It is not easy to scratch but can happen just like it can with regular glass.
I personally have owned tanks that use ppg starphire glass "have a blue edge" and tanks that use low iron glass "have a light green edge" and tanks that use regular glass "have a dark green edge in general" and all were equally scratch resistant.
While I have a tank with starphire, I was able to view a tank at a local store that has a side pane of glass in 1/2" starphire and a front pane in regular 1/2", no idea why they did this but they did. The cool part is that at angle, I could look side by side and compare the two. My observations were as follows...
- Starphire side seemed a very small amount brighter
- Regular glass was just every so slightly darker, and looked like a little contrast was added such as if you were using photoshop to add a tad of contrast which was not a bad thing in any way.
- Both showed coral equally in detail and clarity
- Colors looked equally good with both
So in short, I liked the look of both. Regular glass
ruined nothing for me viewing pleasure wise but in general your tank will have a higher re-sale value if you ever take it down if low iron or starphire is used.
Also be wary of expensive tanks that claim to use actual PPG starphire. Look at the edges of the glass and if they are not light blue or vivid blue in color (depends on length of glass), they may just be using regular low iron glass which is fine, but it is not actual starphire from ppg.
For example, you can see the edge of this tank which in fact uses PPG starphire. Anything else will look light green or dark green that I have found.