Have you tried the IS250/350 many parts interchange with the GS

 

Also since you have the mirror apart, look for tags with name and part numbers. Many times toyota/lexus uses other companies for there parts. So for instance that mirror or digitizer maybe a LG or toshiba etc. That why you can look it up through that part number and sometimes be able to buy direct from a distributor/agent of that company.

 

Ok, I fixed it . . . .
I bought 2012 -2014 LEXUS IS250 IS350 AUTO DIM REAR MIRROR COMPASS HOMELINK OEM and took the mirror out. It is the exact same size mirror. It also has the opening for the compass (but hidden from the front. No black square showing). Exchanged the old mirror with this one and WA-LA! I can see the compass!

Now . . . . will the Auto-Dim still work . . . .