This is a job for Tepox-V. It's a stone stain made by Tenax that we used with a fabricator in a similar situation so he could match the light edge detail with the dyed top. If you used a color enhancer on it and it is still nowhere near the color you need it to be here is what you are going to have to do:
If you already sealed the edge you will need to repolish the edge starting at 100 grit. The reason for this is it will knock out the sealer that you put into the stone making it more porous. This is only necessary if the dye won't take to the stone so I would try that first.
Get the Tepox-V colors that you need to make the edge match the top. It is available in black, blue, brown, green red & yellow. I would practice on some scrap pieces to make sure you have the correct recipe. You want the dyed edge to match the top edge. The Tepox-V may be applied straight to the stone or you can dilute it with a resin based product like Ager or Pectro if you do not want the dye color to be full strength.
Once you have the dye the right color go ahead and wipe it only onto the lighter edge and allow it to stand for 15 minutes then wipe off the excess. Remember that this is a stain and the longer it sits on the stone the more color will get into the stone. If it is still a little lighter do a second coat just like the first.
Once the Tepox-V has dried (24 hours) it is a fairly permanent product. Seal over it and get the customer to sign off on the job. I think you need Brown and yellow, but that is your call. Here are the links for Tepox-V brown & yellow:
http://www.defusco.com/Glues:-Epoxy,-Polyester,-etc.-Waxes-&-other-Stone-treatments/c82_505/p2758/TEPOX-STAIN-FOR-STONE-(1LTR)---BROWN/product_info.htmlhttp://www.defusco.com/Glues:-Epoxy,-Polyester,-etc.-Waxes-&-other-Stone-treatments/c82_505/p2761/TEPOX-STAIN-FOR-STONE-(1LTR)---YELLOW/product_info.htmlIf you need Ager here it is:
http://www.defusco.com/Glues:-Epoxy,-Polyester,-etc.-Ager-Sealer-&-Ager-Tiger-Sealer/c82_503/p1437/AGER---1-LITER/product_info.htmlIf you have questions please call me during the week at 800-289-6834. I will be happy to walk you through this project. In fact, call me before you start so I can give you the benefit of the projects we have done with this type of project and to see what you have done already so you know what to expect.
Glad to be of service,
Mark