"I am attending a conference call with an international business partner. She lives in China and I live in North Carolina. She created the event and invited me as an attendee. The event start time on my calendar is at 9AM but I'm not sure if that is 9AM EST or 9AM UTC."
When you are invited to an event, the start and end times displayed on your calendar will always be in the event time zone and not your time zone. So if you live in the EST time zone and you are invited to an event in the UTC time zone, the event dates and times displayed on your calendar for that event will be in the UTC time zone.
A way to work around this is to export the event to the calendar on your mobile device. Once exported, the event times will be adjusted to your time zone when you view it on your mobile device but they will still be in the event time zone when you view it in the app.