Silver and Mother of Pearl Toasting / Bread Fork

I am about to sell this beautiful fork.
Unfortunately I can only find the RD Number which is marked on it twice.
The RD Number is -143384, which I have dated to be 1890 - 91.
I have looked high and low with a jewellers loupe and can not find any other markings on it. If anyone has any idea on where else to look please help. There is a lot of fine engraving and decoration…maybe its hidden somewhere. The piece is IN MAGNIFICENT condition, so i dont think it has worn off.
It makes a very loud pinging noise that resonates for ages if you flick it ?
If anyone has a value or maker of this beautiful piece I would appreciate your help.
How else can I know its sterling silver or plated?
I can not upload photos on this website…Very frustrating…tried copying pasting …uploading…[/img]

As it has a design registration number we can assume it is English/British. No hallmark means it is, at best, electroplated. And no other marks make it impossible, without access to the design registration information, to give a manufacturer.

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