For my first experiment I tried the small, light blue pearls. These are slightly smaller than the Czech drop beads used in the original design.
I wasn't too happy with how this beaded bead came out for a few reasons. The irregularities in the shapes of the pearls made the resulting beaded bead irregular, which isn't necessarily a bad thing because this can look neat if it's the desired effect. The main reason why I'm not satisfied with this bead is that it's too squishy for my tastes. I like my beaded beads either completely solid, or with less than a millimeter of squish when squeezed on two opposite sides. This one has about five millimeters of squish.
For my next experiment I tried the shiny peacock pearls, which worked quite well in my Bubble Box design.
This bead came out much better. It's a little irregular, but it has a much more acceptable level of squish for my tastes.
For my last experiment I tried using the purple pearls. These are wider at the base than the Czech beads in the original design, but they're still about the same height.
I was really happy with how this beaded bead came out. It's very solid, regular in shape, and it's also a bit bigger than the original design. The drop pearls in this beaded bead do not have high luster, so I compensated for this by using matte metallic seed beads. A big advantage of using these pearls is that they have larger holes than the other two types that I experimented with, so I was able to pass through the finished bead multiple times to stabilize it.
I liked this beaded bead result so much that I made five of them and incorporated them into this necklace, and put it up in my Etsy shop.
So, to summarize, I found that the drop pearls that work best in the Double Bubble Jacks design are regular in shape, slightly larger than 4 x 6 mm Czech drops (especially at the base), and have larger-than-average holes. I also found that since pearls can scratch very easily with say, the tip of a beading needle, I had to be careful to avoid scratching them when I weaving the beaded bead.
I'm looking forward to using freshwater pearl beaded beads in other pieces!