It's been a week since the comeback for Jewelry was teased and the four girls finally had their first comeback performance on this week's Mnet's�M! Countdown. More than a year has gone by since Park Jung Ah and Seo In Young left the group to pursue their solo careers, and it has been one long wait for fans as Star Empire patiently scouted replacement members to join Ha Joo Yeon and Kim Eun Jung. Superstar K Top 10 finalist, Park Se Mi, joined the group 6 months ago, and Kim Ye Won rounded out the�quartet, having just been unveiled earlier this month. After months of preparation, the new Jewelry makes its return with a brand new power 'locking' hip hop dance style and b-girls concept for their comeback single, 'Back It Up'. Check out their performance below!