Purple comparisons, as requested, specifically of MB Psychedelic Purple and Birmingham Pen Co Pop Art Purple (close but BPC not quite as bright!) : r/fountainpens
thINKthursday – Montblanc The Beatles Psychedelic Purple | Anderson Pens Blog
Ink Review #166: Montblanc Beatles — Mountain of Ink
Montblanc The Beatles Psychedelic Purple Ink Review + The Beatles Special Edition First Impressions+ Squishy's Happy Holidays Giveaway! – SquishyInk