Fairly recent necklace by the Scandi brand Hultquist, but very 1920s Art Deco in design and influence.  The modern Scandi brands do not use nickel in their jewellery, according to their bumf:

• “All Hultquist-Copenhagen jewellery is plated with real silver and gold.
• The base is metal alloy and guaranteed nickel free. This base is coated with copper and palladium which gives the plating a better finish and life.
• All stones used are selected Swarovski crystal, quartz, fresh-water pearls or Czech glass beads.
• To optimally care for your jewellery we advise you, not to spray directly with perfume or wear them during bathing and sleeping.”
• This is a second hand, used necklace, in great condition.