I had to make this up because I keep forgetting when the important dates in Jewell's life are:

January 24 (2007)--Skyler's Death

February 2 (1978)--Jewell's Birthday

February 27 (2002)--Cher's Death

April 16 (1995)--Amanda's Birthday

May 8 (1997)--Miscarriage on RhyDin

June 6 (2007)--Stephen and Jewell's Wedding Anniversary

September 5 (1992)--Miscarriage on Aquarius

September 25 (1999)--Moradin's Birthday

November 4 (2002)--Devyn and Kerrick's Birthday

December 27 (2001)--Eva Jade, Oz, and Raven's Birthday

December 18 (2009)--Jewell leaves RhyDin. The children stop aging.

This leaves the kids' ages as follows (adding one more year because everyone spent two years on Aquarius following the birth of Kerrick and Devyn but only one year passed in RhyDin):
Amanda 15
Moradin 11
Eva-Jade/Raven/Oz 8 (would be 9 in nine days)
Kerrick/Devyn 8

Jewell's approximate age: 236 give or take a decade or so since I have not determined exactly how long she spent in Faerie.

Fantasy time is a pain in my butt.