When gouting coral stone it's best to do this in 2 steps. First with a gout bad fill the cavity about half way first and let it set for 5 min, Then come back and over fill the cavity and let it set. After the grout set and get stif then pack it tight using a sticker. Then trim off the excess grout and let set. Use a sponge and water to detail the gout joint once it is hard. Only detail the stone not the grout. To much water will change the color of the grout.
