Vintage Egyptian 18ct Gold 15ct approx stone pendant

18ct gold Egyptian 15ct citrine pendant, due to hallmarks the pendant is 18ct only hallmarked with the iv like Egyptian mark for 18ct gold. Item definately has age unsure how old it is. The stone is orange in colour and very near flawless, item has not been and definately not heat tested. A very nice little pendant which deserves a nice high ct gold chain. Please help with age? Item weighs 16.5ct if it was a diamond don't know the conversion for citrine. Weight is over 5gms of which under 1gm is gold.
Let me know your thoughts I would like to know approx age as I no longer want it.
Lee