Any topcoat will bring out that shimmer in the curl. Shellac is a great sealer and will help get more uniform results with any stain, dye or finish you decide to use. I may be wrong but it's been my experience that the more gloss in the finish the more chatoyance you get. Especially if you rub out the finish to a high gloss. The finer the scratches in the finish allows more light to penetrate to the curl in the wood giving it the shimmer or chatoyance.