Linde Star History and Information (2024)

The Story of Linde Stars

The following article is based on excerpts from aninterview with Mr. Jack Burdick, co-inventor at U.C.C., Linde division.

MJ:Mr. Burdick, would you tell us how youhappened to develop the star?

Burdick: I must go back to about 1920. In Europe as in all otherplaces since, synthetic blue sapphire has never been a satisfactorymaterial. Regardless of how you grow it, the color seems tosegregate on the outside of the boule. So in Europe at one timethey were attempting to get better distribution of the color in bluesapphire. They kept adding magnesium oxide to the sapphire untilfinally they made spinel. When they made blue spinel, theythought it was blue sapphire. In fact, it was sold for bluesapphire for a considerable period of time before it was detected thatit wasn't blue sapphire at all. It was spinel.

In about 1947 we were attempting to do the samething the Europeans were trying to do back in 1925 . . .that was, to try to improve the blue sapphire by getting a moreuniformly colored material. You'll remember we said the color ofblue sapphire was due to iron and titania. We thought thatperhaps we could eliminate the iron and get the blue color with titaniaif we properly heat treated the material after we grew it. So, we left the iron out of the formula and we putonly titania in it. Then our plan was to heat this in a furnacewith a reducing atmosphere. We felt that if we reduced the TiO2we would be able to get a blue color without the presence ofiron. So we manufactured these sapphires with only titania inthem. We heated them for several days in a furnace at a hightemperature. And when we took them out, they were star sapphires.

However, we didn't recognize them immediately asbeing such. But we did see that they were different. Theywere slightly milky. They had some indication that there weredifferent rays within the sapphire. We didn't know if we hadcat's-eyes, if we had stars, or exactly what we had. However, mybrother was an amateur lapidary and had a little shop in his house onlya few blocks away. So I took some of these boules that had beenheat treated and grown only with titania as the colorant to his houseand told him to cut cabochons from them. I suggested that if henotice anything particularly, that he should telephone me.

So, this Sunday in late December, 1947, he called meand said he thought these stones looked different. I went over tohis house and looked at them under his fluorescent light. Theydid look a little different, but not particularly so. In thecourse of the conversation, we decided to go out on the back porch fora cigarette. It was a nice, sunshiny day, even though itwas winter. We carried one of these stones on a dop stick withus. As we stepped on the porch and the sun hit the dop stick. . . there was the star!

So you might say . . . like theEuropeans in making spinel . . . they were trying todo something different. We also, at the time we made stars weretrying to do something different.

MJ:Mr. Burdick, Did youhave it in mind to create gemstones?

At that time Linde's business was both industrialand jewelry. However, there were no stars. Some blue aswell as some ruby stones as well as other colors were being sold tolapidaries who made regular faceted gem stones from them.

MJ:Mr. Burdick,Then would you say that the discovery of the star was an accident?

Burdick: You might say that it was an accident.

However, some work had been done both by us and by many other people intrying to make stars. The point is, we were successful when wewere trying to do something else. Had we not been aware of what astar stone was, we might have passed over this thing and neverdeveloped it into the business that it is today. Incidently, we sold about $100,000.00 worth of starsthe first six months we made them. I think this proves that therewas a need for them.

MJ: Can you thinkof any other facts that you think might interest the jeweler?

Burdick: It might be interesting to imagine how nature madestars. We know that in natural stars there is titaniapresent. We know that in natural stars this titania is present asan independant phase oriented in exactly the same manner as it is inour synthetic stars. It would be easy to imagine that a naturalstar was formed at very high temperature in the earth. And as theearth cooled this crystal went through the temperature range say from1100 to 1500 degrees Centigrade . . . the differencebeing that we keep them in that temperature range for a few days.

But nature kept them in that temperature range for millions ofyears. So the thing that causes the asterism in natural andsynthetic stars is identical, and you might say that at least some ofthe processing is identical.

Linde patented their star sapphires in November of1949. Production was discontinued in 1974 due tooverseas competition.