686 engraved with a heart and the number four. What does that mean? and a particular

[lucamiata]

 

[lucamiata]

 

[lucamiata]

 

[jughed440]

Posted the same question before. Quote, from the guy who knows

It is the fitters mark. Some of the old time fitters had pretty neat stamps and they would pass them on to some of the newer fitters. Roy

this double stamp is on a 25-5

 

[Mack]

That is a stamp, not an engraving.

 

[lucamiata]

thanks guys! ps. I noticed on the bridge there 's one with numbers what does it mean? then always in the grip part of the frame of a letter j.