Maintenance for the week of May 13:
• [COMPLETE] ESO Store and Account System for maintenance – May 14, 9:00AM EDT (13:00 UTC) - 12:00PM EDT (16:00 UTC)
You've found 5 Antiquities that rank, and need to find a total of 12 (or their equivalent in achievements, no I don't know either) to reach the next rank.
The 700 is probably the total number of Antiquities/chevos altogether you need to max out the skill line.