I've always called these types of earrings 'bendy hoops' technical I know! 
 
The structure of these hoops mean that they are opened and closed by 'bending' one end of the earring forwards or backwards. This releases the hook from the hoop so you can pop it in/remove it. Don't be afraid that by gently bending them you'll break them, you won't.
 
Material - 9ct gold 
Hallmarks - none
Country of origin - likely England
Drop - 3.5cm
Width - 3.5cm
Weight - 1.9g
Condition - good pre loved condition