Here's the result of scatter plot using Matplotlib

And now here's the result of calling scatter plot using Pandas

Is there bug in Pandas scatter function or is it supposed to work like this?
I think the grey area you see is the boundary of each point. Use the argument edgecolors='none' or edgecolors='black' to get the same result as you get with matplotlib (see also http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.scatter)
3.4.3, pandas0.17.1, matplotlib1.5.0. I used diamonds fromggplotpackage.