Riyadh is 8 hours ahead of Medellín
Best overlap: 8:00 AM to 10:00 AM in Medellín is 4:00 PM to 6:00 PM in Riyadh.
For a call that suits both sides, look at 8:00 AM to 10:00 AM in Medellín / 4:00 PM to 6:00 PM in Riyadh. Since Riyadh is 8 hours ahead of Medellín, the overlap is narrow (about 2 hours); a single, well-protected slot beats hunting for time each week.