(sold) This is a 1946 Blue Diamond Parker 51 Vacumatic in Blue Cedar, with a 14k Fine nib and a gold-filled cap. The pen has been restored, which included a complete disassembly, thorough cleaning, an overhaul of the filling mechanism (using best practices and high-quality replacement components), ink flow adjustment, nib tuning, and a gentle hand polish.
This is a beautiful, rare pen, and it's in excellent condition. Parker claimed, in its advertising campaign in the late 1940s, that the 51 was the world's most wanted pen. Apparently, 77 surveys in 22 countries were carried out to arrive at this conclusion. And who could argue with that? During that time, Parker had factories in the US, Canada, England, and, later, even in Argentina. This particular pen was made in 1946 in Canada, which makes it the "first year" Canadian production.
The Parker 51 is a pen that is still the most frequently recommended vintage pen for beginners. Whether it's at a pen show, Twitter, FPN, or your local pen club, vintage pen enthusiasts are likely to praise the 51 for being uniquely suited to novices. I think the biggest advantage of the 51 is incredible ease of use. Its ergonomics make it suitable for most hand sizes and grips. The long, stepless section is pleasant to hold. The hooded nib protects the pen from drying out, the slip cap quick to deploy. The nib is shaped and ground in such a way that it is forgiving of angle and rotation. The pen writes under the lightest touch, but you can write equally well with a heavy hand, without adverse effects. It's also a very classy, sleek, and professional-looking pen, regardless of your taste in fashion or work environment, it's going to look good.
I tuned the nib to write smoothly, with consistent, generous, yet restrained flow. You can use the pen confidently to write at work or at school, on all kinds of paper. The line is a true-to-size Parker Fine line, which puts it just south of modern Western Fine. The filling mechanism works smoothly, efficiently, and holds a lot of ink.
Cosmetically, this is one of the nicest pens from that era I've seen, without any flaws or defects, and with just negligible surface wear, not visible with the naked eye. The gold-filled cap is gleaming, free from scratches or dents. The jewel is clear and the imprint strong.