Ok sorry for the delay. I have been interrupted about 30 times to do anything else but this today with work stuff. Coworker iPhone drama, etc.
Also, what is lower half length % and star length %, any significance?
Definitions:
Star Length Percentage:
The Star Facets are the small, triangular facets found next to the table facet on top of the diamond, The length percentage is the projected distance between the table edge and the point of a star facet.
Lower-Half Length Percentage:
Average lower-half length * relative to the distance between the culet and the girdle.
(*Lower-half Length: the horizontal distance between the girdle edge and where the two pavilion mains meet)
The longer the lower girdle facets, the more fire and scintillation the stone should have relative to the crown facets to a point (you don't want to go too much beyond 80%)--assuming the angles match up. Ideally you want the Lower Half to be around 75-80. Since the GIA usually rounds the numbers, it could be anywhere within the range if it's a 75 or 80. If the stars are around a 50-55% you will get great light return back through those facets. There is a direct correlation between the percentage of the stars and the lower half facets, the larger that percentage on the lower half, the skinnier the arrows are and eventually with a higher % of star facet the better the amount of light return.
Short answer--the higher the percentage on the lower half, the skinnier the arrows but the more fire and scintillation the stone should have assuming the angles still are appropriately aligned for ideal cut.
Regarding the stones you've posted...Those 1.45/1.48s you probably should eliminate unless in person you adore either of them, Esp the new one. They are facing up too small for their carat weight. A 1.5ct stone should be around 7.4mm, and those are in the 7.2-7.25 range. Really all of them aren't facing up properly. Which is why I've made comments a few time about their depth being a little too deep, but their diameters are really bothersome on these two in the 1.4x range. Those stones are going to look like a 1.35ct diamond (7.2mm) not like the almost 1.5ct you're paying for. The best of all so far is that 1.39. It's the best diameter for it's size, still a tiny bit small for it's weight but not like the others.