You are looking at a guitar amplifier indicator lamp jewel. I call this the 'rose quartz' jewel. This is made from a quartz stone jewel and it has a nice pinkish rose, slightly moon-like opaque quality. It is smooth and round on the outside. This jewel fits any 'Fender style' lamp assembly with the screw on jewel - these assemblies have also been used on many other amplifier brands over the years - email me with a picture of yours if you are not sure.
The picture is shown with the jewel lamp only (Fender amp not included). Your amp should have the assembly already - the original just screws off and this one screws on (if you need the assembly, or the #47 lamp, we have these available in our store). Larger quantities may be available for amplifier builders, etc. Also check our store for many other types of unusual jewel lamps, as well as amplifier channel/reverb/trem switchers, A/B boxes and A/B/Y boxes, all with jewel lamps. Local pickup is available at our Baltimore studio. Thanks.
Dave Nachodsky
Invisible Sound Studios, Inc
4401 Eastern Avenue ste. 7
Baltimore, Maryland 21224
Home of The North American Guitar Amplifier Museum