I saved this image from BCN about 6 years ago. My notes say that this is from the Levin & Co.(barely visible under the title on the card), and dates from 1850s - 1870s. You can see one large yellow disk bead with rounded edges on the bottom strand.

The Picard exhibit on Pre-1900 Sample Cards show a good number of monochrome beads but only the more common tapered-edge yellow disk beads.

Because of the discussion about the use of uranium glass - I think I'll check my similar "greasy yellow" large disks to see if they were colored with uranium salts, since as was pointed out, the density on these is very high.