The small discolouration on the cap and the general appearance makes me think it's ebonite but I couldn't find any information on line to confirm this. The large nib is marked 18k/750 PILOT.
It has two breather holes and the JIS mark on one side and 1174 on the other. The size indication is though it really looks and writes like a Stub. The close up photos show it has a squared off tip rather than a big round ball of iridium. It writes with a wet, smooth line and has a bit of useful flex and significant line variation between vertical and horizontal strokes. The barrel has what is probably a commercial engraving: "TPWII Vetswood, Eidai, Toyomenka".
I looked it up and can't tell if it's a Japanese company specialising in wood products or transistor radios. Regardless, it is quite discreet on the matte black barrel. The large, striking cap band is marked PLOT GRANDEE 22K AGM. It's just a guess but this might mean it's vermeil -- 22k gold plating on silver. I do not think the cap band is solid 22k gold.
The only marking other than these is a Pilot logo on the cap top. This is a large pen for a Japanese pen of this time. Length capped: 14cm (5 1/2).Length posted 16cm (6 1/4). I used the pen refilling Pilot cartridges but the large CON-50 converter should fit because the barrel is quite long and thick. Pilot's smaller converters will certainly fit. The item "Pilot Grandee Golden Nugget FP. Excellent condition" is in sale since Friday, June 28, 2019.
This item is in the category "Collectibles\Pens & Writing Instruments\Pens\Fountain Pens\Pilot". The seller is "poochnyck" and is located in Toronto, Ontario.
This item can be shipped to North, South, or Latin America, all countries in Europe, all countries in continental Asia, Australia.