The Finetec Pearl Metallic Ink Palette is by far the best out there. Fantastic shades and very long-lasting.
Made of mica, a natural mineral that offers a wide variety of metallic shades, from gold and silver to iridescent, shining pearl colours. Activate with a little water on the palette and apply to the nib with a brush. Adheres to all absorbent surfaces, such as paper, wood, gypsum, etc.
(There are tons of forums, links and youtube videos that show you how to best use this product. Here's one we like: http://www.aninarubio.com/blog/2014/11/4/mighty-mighty-finetec)
To get started in Modern Calligraphy or for more tips, tricks and techniques pick up a copy of our book, 'Modern Calligraphy: A Step-by-Step Guide to Mastering the Art of Creativity'.