https://www.khmer24.com/vintage-omega-constellation-18k-gold-model-166-056—168-042-for-sale-adid-10098954?fbclid=IwAR2npAbaqlkQA8zKvm8RKUMIuzJ2TX7Pe0YG8Tqt4gLNKZRT654mn9mZcqU

No box, no papers, no original strap.

He has it listed as “Vintage Omega Constellation 18K Gold Model 166.056 - 168.042”. Anything I should look at specifically when looking at the movement/dial/crown for knock-offs? Which year and model and movement is this? What’s the weight in just 18k gold? How can I tell its properly functioning or in need of servicing? Any advice helpful. Thx in advance for any help folks.