Blue Hemimorphite, Sa Duchessa Mine, Sardinia

Hi all,
quite unusual that i post in the valuation thread but i am not very familiar with these blue hemis from Sardinia. I acquired it yesterday in a mid 20th century collection and it caught my attention as it fits into my prey pattern for my own aestetics collection. 2 questions:
1st - what do you think about the quality of the specimen (9 x 5 x 3.5 cm) - would you consider this to be an above average example or below .. etc etc ... i think our italian friends could tell me more about it. The colour is really striking blue with almost glassy lustrous surface.
2nd - any idea of a value - and please give conservative estimates ...
The specimen is NOT for sale - i want to keep it in my collection.






Thanks for your input,
cheers
Roger