Black diamonds, those once ignored midnight gemstones, are proving their worth as well, as they continue to fascinate jewellery wearers.

In their desire to create appealing jewellery, designers are expanding their horizons on every level.

Styles run the gamut from lavish to understated, classic to trendy and silvery white to wildly colourful. Cropping up are less conventional materials too, including leather, rubber, silk, lacquer, oxidised silver and titanium.

Whether inspired by nature or man-made objects, designers are drawing on various sources for ideas.

'Mine are from observing people, from movies, from books, from life, from travelling,' said Australian designer Jan Logan.

Her Bola necklace, an idea derived from the throwing device that South American gauchos use to capture cattle or game, features a long strand of emeralds, rubies, sapphires or other gemstones with pearls on each end. 'You can tie it in a knot around your neck,' she suggested.

The necklace can also be worn around the waist or wrapped around the wrist.

A fondness for black diamonds has led her to combine black and white diamonds, South Sea pearls and white topaz together in a stylish floral necklace set in sterling silver.

Not known for shy and retiring jewellery, Logan feels the move towards size reflects an underlying feel-good attitude.

'I think there's a certain confidence and amount of affluence in the world,' she said. 'It just reflects a mood at the moment.'

Italian artistry is evident in Italian fine jewellery maker Loffredo's extravagant and chic designs. Best known for its coral jewellery, the company keeps fashion and a strong focus on design in mind as it plays with colour and incorporates a host of other gemstones into its pieces, including chrysoprase, turquoise, diamonds and emeralds.

'This year we are working with shell combined with coral, and also bright green chrysoprase,' said Valentina Loffredo, the owner of the company and one of its designers.

'It sounds strange, but turquoise combined with orange coral and pink coral and set in rose gold looks very nice.' Warm reddish tones dominate Loffredo's colour palette, but these are never monotonous. 'There are so many shades of orange and pink,' Loffredo said.

A look that is too monochromatic would be out of step with the company's brightly coloured jewellery.

The emphasis at Danish brand Georg Jensen is on the Nordic sensuality of 'pure, modern organic shapes and forms'. Timeless, elegant designs have been the company's signature style since the firm's early 20th-century days. Many of its best-selling designs date from the 1950's through to the 1970's.

'We don't follow fashion trends. We are much more about a celebration of shape and form that will last forever,' noted the company's international marketing director Gord Ray.

Rubber cords and leather, which currently seem trendy, have been used by the company off and on for years.

While diamonds set in sterling silver or yellow or white gold are its core product base, the company has ventured into more colour with a line of cocktail rings featuring large centre stones of amethyst, rose quartz, citrine and other coloured gemstones.

'Pastel-coloured stones have become more popular, and with the resurgence of cocktail rings in the past few years, there has been a need for large centre stones,' he said.

Italian brand Pianegonda's lavish and passionate designs are a reflection of designer Franco Pianegonda's heart and soul. He aims to 'create a world of silver, gold and gems never seen before, rich in poetry, strength and beauty'.

Pianegonda works mainly in sterling silver and 18-carat yellow gold, and is directly influenced by fashion and art trends. The heart, cross, circle and key are the company's four main design themes.

The Glitter ring, a knotted design with pave diamonds set in sterling silver, is the company's top seller.

'We don't go for big diamonds or rubies. With a pave setting, we get a big effect and shades of colour,' said Renaud Litre, Pianegonda's Asia-Pacific managing director.

Launched this year is a collection that combines silver and lacquer. 'The response has been tremendous. We use red, black and white lacquer on sterling silver,' Mr Litre said. Coming up next year is a line of sterling silver and pearl jewellery.