If you're the kind of person that browses through toy advertisements, marketing announcements or product descriptions of Filly toys, there's a decent chance that you've noticed all the mentions of the toys having Swarovski elements. This is most commonly observed in the crowns of the various characters, in most of which a small gem or crystal can be found.
In addition to Swarovski's own products, as well as directly supplying high-end companies (mostly fashion designers and furniture), the term "Made with Swarovski© elements" that is usually found on Filly blindbags, signify that Swarovski merely supplied crystals to a third-party manufacturer, and they appear to have a whole lot of companies in that latter range. While this allows designating the resulting products as Swarovski elements or that they're "made with Swarovski© crystals", they cannot be branded as proper Swarovski products and aren't guaranteed to meet their quality standards. This presumably makes it more possible for £5 blindbag figures and figures following £4 magazines to carry these Swarovski elements.
Keep in mind, that the second tier in the above paragraph, that with the direct supplies, are based around a sub-company whose old name actually was Swarovski Elements, which muddied the issue a whole lot. The sub-company is now known as Crystals From Swarovski.
Appearances in Filly material
The Swarovski elements generally appear in the crowns of the character toys in the present canon brands, and usually as one big gem. Among the exceptions are Princess Sparkle, who has many gems of many colors in her crown.
This carried over to Filly Funtasia, where nearly all characters maintain their crown elements, with the main exceptions in the show being Will who has many tiny red gems, and Loki who has a headband with a star-shaped figure on it.