Sadly, it is a problem even with under 1ct stones. I had a pair of .76 cttw lab diamond studs which I hated. The performance was so bad - I had to work hard to get any fire out of them. These were IGI graded stones that rated a .9 and 1.2 on the HCA scale and were super ideal cut so, theoretically, should have performed very well. I gave up, returned them and purchased WF mined diamond studs which, needless to say, are freakin spectacular and worth every penny I paid.
On the other hand, I have a 1.13 ct lab diamond ring graded by GCAL also super ideal cut which is amazing! It scored a .7 on the HCA scale and is as beautiful as my WF studs. I think I got very lucky with my ring. If I were to purchase a lab diamond again, I would purchase from a vendor screening for stria and its impact on performance. August Vintage comes to mind.