Find your opponent's gems in this mind-bending deduction duel

A wonderfully brain-burny, head-to-head, gem-hunting twist on an all-time classic: Battleship. You are gem hunters racing to determine the positions of 5-7 colored gems on your opponent's mine grid. Take turns firing a wave (line) from any edge of the grid. The exit point and the color of the wave tell you the angles and colors of gems the wave touched in its path. Be the first to identify the exact dispositions of your opponent's gems, and you claim rights to the Orapa Mine!