How to get empty markers, Plots, gr() backend

If one is not too choosy, pseudo-transparency is possible:

using Plots; gr()
M = rand(10,2)
scatter(M[:,1], M[:,2], mc=:white, msc=:darkred, msw=2, label="Am I transparent?")
plot!(M[:,1], M[:,2], ls=:dot, c=:red, framestyle=:box, grid = false)