Good evening, Paul,
Thank you for submitting photographs to Mearto for appraisal.
Based on the photographs and information provided, your Tiffany 18K yellow gold box weighing 504 grams has a melt-weight value of $14,888 at the current rate of $29.54 per gram for 18K yellow gold. That said, pieces made by Tiffany sometimes command a premium so I have valued your box with the melt weight as the low estimate.
I hope the above information has been useful to you. Please let us know if you have additional questions, and thank you for using Mearto.