i haven't seen the mfg's specific color, but i can tell you that technically, chartreuse is supposed to be a very bright strong lemon yellow, with slight green tint. it was one of the new hot colors out of Europe 5 yrs ago.
more importantly - what color is the frame on your table? cause if it's brown, it's going to look like puke. black or gray would make it pop! can't the mfg send you an actual swatch (or 3"x3" fabric cutting)? go to WalMart & buy a twin sized flat sheet ($10) in a similar color. or Party City & find wrapping paper. lay it down on your table under the lights. and live with it for a few days - then you'll have your answer.
good luck with chalk. is ChicagoRJ's Russian chalk the kind that doesn't leave residue & is basically clear? somebody needs to produce clear chalk.
wait - this is 3 yrs old? hell, the color is probably discontinued by now!