I think that sounds pretty good. It stands to reason that they both would have amassed a large amount of sapphires, and they have both been actively experimenting with them. Perhaps as they experimented, the two masses of sapphires resonated with each other and that's why the portal opened. It seems like it would fit the characters best if Urkwia was the one who actually opened the portal, and Telio threw caution to the wind and hopped through it.